diff --git a/connect/exceptions.py b/connect/exceptions.py
index 1d52660..05496e3 100644
--- a/connect/exceptions.py
+++ b/connect/exceptions.py
@@ -84,6 +84,7 @@ class ServerError(Exception):
     """
 
     def __init__(self, error):
+        self.error = error
         super(ServerError, self).__init__(str(error), error.error_code)
 
 
diff --git a/connect/models/__init__.py b/connect/models/__init__.py
index 93b52b6..5a49335 100644
--- a/connect/models/__init__.py
+++ b/connect/models/__init__.py
@@ -13,6 +13,7 @@
 from .asset import Asset
 from .base import BaseModel
 from .billing import Billing
+from .commitment import Commitment
 from .company import Company
 from .configuration import Configuration
 from .connection import Connection
@@ -55,6 +56,8 @@
 from .tier_account_request import TierAccountRequest
 from .tier_config import TierConfig
 from .tier_config_request import TierConfigRequest
+from .ui import UI
+from .unit import Unit
 from .usage_file import UsageFile
 from .usage_listing import UsageListing
 from .usage_record import UsageRecord
@@ -83,6 +86,7 @@
     'BillingRequest',
     'Company',
     'Configuration',
+    'Commitment',
     'Connection',
     'Constraints',
     'Contact',
@@ -125,6 +129,8 @@
     'TierAccounts',
     'TierConfig',
     'TierConfigRequest',
+    'UI',
+    'Unit',
     'UsageFile',
     'UsageListing',
     'UsageRecord',
diff --git a/connect/models/commitment.py b/connect/models/commitment.py
new file mode 100644
index 0000000..aab4c89
--- /dev/null
+++ b/connect/models/commitment.py
@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+
+# This file is part of the Ingram Micro Cloud Blue Connect SDK.
+# Copyright (c) 2019-2020 Ingram Micro. All Rights Reserved.
+
+from .base import BaseModel
+from .schemas import CommitmentSchema
+
+
+class Commitment(BaseModel):
+    """ Billing commitment object. """
+
+    _schema = CommitmentSchema()
+
+    multiplier = None  # type: str
+    """ (str) Commitment multiplier. """
+
+    count = None  # type: int
+    """ (int) Number of commitments. """
diff --git a/connect/models/item.py b/connect/models/item.py
index 6f54166..8d078cf 100644
--- a/connect/models/item.py
+++ b/connect/models/item.py
@@ -6,9 +6,12 @@
 from typing import List, Optional, Union
 
 from .base import BaseModel
+from .commitment import Commitment
 from .param import Param
 from .renewal import Renewal
 from .schemas import ItemSchema
+from .ui import UI
+from .unit import Unit
 
 
 class Item(BaseModel):
@@ -55,6 +58,15 @@ class Item(BaseModel):
     name = None  # type: str
     """ (str) Name. """
 
+    unit = None  # type: Unit
+    """ (Unit) Measure unit. """
+
+    commitment = None  # type: Optional[Commitment]
+    """ (Commitment) item billing commitment. """
+
+    ui = None  # type: UI
+    """ (UI) UI visibility. """
+
     def get_param_by_id(self, param_id):
         """ Get a parameter of the item.
 
diff --git a/connect/models/schemas.py b/connect/models/schemas.py
index 6686f72..e9ad096 100644
--- a/connect/models/schemas.py
+++ b/connect/models/schemas.py
@@ -9,6 +9,11 @@
 
 
 class BaseSchema(Schema):
+
+    def __init__(self, *args, **kwargs):
+        # kwargs['strict'] = True
+        super(BaseSchema, self).__init__(*args, **kwargs)
+
     id = fields.Str()
 
     # Set allow_none to True in all fields
@@ -334,18 +339,50 @@ def make_object(self, data):
         return Param(**data)
 
 
+class UISchema(BaseSchema):
+    visibility = fields.Bool()
+    @post_load
+    def make_object(self, data):
+        from connect.models import UI
+        return UI(**data)
+
+
+class UnitSchema(BaseSchema):
+    title = fields.Str()
+    unit = fields.Str()
+
+    @post_load
+    def make_object(self, data):
+        from connect.models import Unit
+        return Unit(**data)
+
+
+class CommitmentSchema(BaseSchema):
+    multiplier = fields.Str()
+    count = fields.Int()
+
+    @post_load
+    def make_object(self, data):
+        from connect.models import Commitment
+        return Commitment(**data)
+
+
 class ItemSchema(BaseSchema):
     mpn = fields.Str()
     quantity = QuantityField()
     old_quantity = QuantityField()
     renewal = fields.Nested(RenewalSchema)
+    unit = fields.Nested(UnitSchema)
+    commitment = fields.Nested(CommitmentSchema)
     params = fields.Nested(ParamSchema, many=True)
     display_name = fields.Str()
     global_id = fields.Str()
     item_type = fields.Str()
+    description = fields.Str()
     period = fields.Str()
     type = fields.Str()
     name = fields.Str()
+    ui = fields.Nested(UISchema)
 
     @post_load
     def make_object(self, data):
@@ -828,8 +865,8 @@ def make_object(self, data):
 
 
 class AttributesSchema(BaseSchema):
-    provider = fields.Nested(CompanySchema, only=('external_id'))
-    vendor = fields.Nested(CompanySchema, only=('external_id'))
+    provider = fields.Nested(CompanySchema, only=('external_id',))
+    vendor = fields.Nested(CompanySchema, only=('external_id',))
 
     @post_load
     def make_object(self, data):
diff --git a/connect/models/ui.py b/connect/models/ui.py
new file mode 100644
index 0000000..43371dc
--- /dev/null
+++ b/connect/models/ui.py
@@ -0,0 +1,16 @@
+# -*- coding: utf-8 -*-
+
+# This file is part of the Ingram Micro Cloud Blue Connect SDK.
+# Copyright (c) 2019-2020 Ingram Micro. All Rights Reserved.
+
+from .base import BaseModel
+from .schemas import UISchema
+
+
+class UI(BaseModel):
+    """ UI object. """
+
+    _schema = UISchema()
+
+    visibility = None  # type: bool
+    """ (str) Item UI visibility. """
diff --git a/connect/models/unit.py b/connect/models/unit.py
new file mode 100644
index 0000000..d724bad
--- /dev/null
+++ b/connect/models/unit.py
@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+
+# This file is part of the Ingram Micro Cloud Blue Connect SDK.
+# Copyright (c) 2019-2020 Ingram Micro. All Rights Reserved.
+
+from .base import BaseModel
+from .schemas import UnitSchema
+
+
+class Unit(BaseModel):
+    """ Unit object. """
+
+    _schema = UnitSchema()
+
+    title = None  # type: str
+    """ (str) Name of measure unit. """
+
+    unit = None  # type: str
+    """ (str) unit code of measure unit. """
diff --git a/connect/resources/base.py b/connect/resources/base.py
index 97c0f69..449093d 100644
--- a/connect/resources/base.py
+++ b/connect/resources/base.py
@@ -140,11 +140,11 @@ class BaseResource(object):
 
     def __init__(self, config=None):
         # Set client
-        if not self.__class__.resource:
+        if not self.resource:
             raise AttributeError('Resource name not specified in class {}. '
                                  'Add an attribute `resource` with the name of the resource'
                                  .format(self.__class__.__name__))
-        self._api = ApiClient(config, self.__class__.resource)
+        self._api = ApiClient(config, self.resource)
 
     @property
     def config(self):
@@ -161,12 +161,15 @@ def get(self, pk):
 
     def filters(self, **kwargs):
         # type: (Dict[str, Any]) -> Dict[str, Any]
-        filters = {}
+        query = Query()
         if self.limit:
-            filters['limit'] = self.limit
+            query = query.limit(self.limit)
         for key, val in kwargs.items():
-            filters[key] = val
-        return filters
+            if isinstance(val, (list, tuple)):
+                query = query.in_(key, val)
+            else:
+                query = query.equal(key, val)
+        return query
 
     @function_log
     def search(self, filters=None):
@@ -208,3 +211,14 @@ def update(self, id_obj, body):
 
     def list(self, filters=None):
         return self.search(filters)
+
+
+class NestedResource(BaseResource):
+    """Base class for all nested resources"""
+
+    def __init__(self, config=None, parent_path=''):
+        self.resource = '{}/{}'.format(
+            parent_path,
+            self.__class__.resource,
+        )
+        super(NestedResource, self).__init__(config)
diff --git a/connect/resources/fulfillment_automation.py b/connect/resources/fulfillment_automation.py
index 41a481c..3f1f456 100644
--- a/connect/resources/fulfillment_automation.py
+++ b/connect/resources/fulfillment_automation.py
@@ -68,10 +68,10 @@ def filters(self, status='pending', **kwargs):
         :return: The set of filters for this resource.
         :rtype: dict[str,Any]
         """
-        filters = super(FulfillmentAutomation, self).filters(status=status, **kwargs)
+        query = super(FulfillmentAutomation, self).filters(status=status, **kwargs)
         if self.config.products:
-            filters['asset.product.id__in'] = ','.join(self.config.products)
-        return filters
+            query.in_('asset.product.id', self.config.products)
+        return query
 
     @function_log
     def dispatch(self, request):
diff --git a/connect/resources/product.py b/connect/resources/product.py
index 0f446ff..3bd79b4 100644
--- a/connect/resources/product.py
+++ b/connect/resources/product.py
@@ -1,5 +1,12 @@
 import json
-from .base import BaseResource
+
+from .base import BaseResource, NestedResource
+from ..models import Product, Item
+
+
+class ProductItemResource(NestedResource):
+    resource = 'items'
+    model_class = Item
 
 
 class ProductsResource(BaseResource):
@@ -7,6 +14,7 @@ class ProductsResource(BaseResource):
         :param Config config: Config object or ``None`` to use environment config (default).
     """
     resource = 'products'
+    model_class = Product
 
     def list_parameters(self, product_id):
         """ List parameters for a product.
@@ -75,3 +83,7 @@ def delete_parameter(self, product_id, parameter_id):
             path=path
         )
         return response
+
+    def items(self, product_id):
+        """Returns the ProductItemResource resource"""
+        return ProductItemResource(self.config, 'products/{}'.format(product_id))
diff --git a/connect/resources/tier_config_automation.py b/connect/resources/tier_config_automation.py
index b980589..4f57066 100644
--- a/connect/resources/tier_config_automation.py
+++ b/connect/resources/tier_config_automation.py
@@ -57,10 +57,10 @@ def filters(self, status='pending', **kwargs):
         :return: The set of filters for this resource.
         :rtype: dict[str,Any]
         """
-        filters = super(TierConfigAutomation, self).filters(status=status, **kwargs)
+        query = super(TierConfigAutomation, self).filters(status=status, **kwargs)
         if self.config.products:
-            filters['configuration.product.id'] = ','.join(self.config.products)
-        return filters
+            query.in_('configuration.product.id', self.config.products)
+        return query
 
     @function_log
     def dispatch(self, request):
diff --git a/connect/resources/usage_automation.py b/connect/resources/usage_automation.py
index ed8e162..b7a187e 100644
--- a/connect/resources/usage_automation.py
+++ b/connect/resources/usage_automation.py
@@ -35,10 +35,10 @@ def filters(self, status='listed', **kwargs):
         :return: The set of filters for this resource.
         :rtype: dict[str,Any]
         """
-        filters = super(UsageAutomation, self).filters(status, **kwargs)
+        query = super(UsageAutomation, self).filters(status, **kwargs)
         if self.config.products:
-            filters['product__id'] = ','.join(self.config.products)
-        return filters
+            query.in_('product.id', self.config.products)
+        return query
 
     def dispatch(self, request):
         # type: (UsageListing) -> str
diff --git a/connect/resources/usage_file_automation.py b/connect/resources/usage_file_automation.py
index 7060898..0f04188 100644
--- a/connect/resources/usage_file_automation.py
+++ b/connect/resources/usage_file_automation.py
@@ -30,10 +30,10 @@ def filters(self, status='ready', **kwargs):
         :return: The set of filters for this resource.
         :rtype: dict[str,Any]
         """
-        filters = super(UsageFileAutomation, self).filters(status, **kwargs)
+        query = super(UsageFileAutomation, self).filters(status, **kwargs)
         if self.config.products:
-            filters['product_id'] = ','.join(self.config.products)
-        return filters
+            query.in_('product_id', self.config.products)
+        return query
 
     def dispatch(self, request):
         # type: (UsageFile) -> str
diff --git a/requirements/sdk.txt b/requirements/sdk.txt
index c110d90..1a4539e 100644
--- a/requirements/sdk.txt
+++ b/requirements/sdk.txt
@@ -1,6 +1,6 @@
 deprecation==2.0.6
 marshmallow==2.18.0
-openpyxl==2.5.14
+openpyxl>=2.5.14
 requests==2.21.0
 six==1.12.0
 pathlib==1.0.1
diff --git a/tests/test_billing_request.py b/tests/test_billing_request.py
index 7cedbc6..fa70637 100644
--- a/tests/test_billing_request.py
+++ b/tests/test_billing_request.py
@@ -85,9 +85,8 @@ def test_list_billing_request_ok(self, get_mock):
         get_mock.assert_has_calls([
             call(
                 headers={'Authorization': 'ApiKey XXXX:YYYYY', 'Content-Type': 'application/json'},
-                params={'limit': 100},
                 timeout=300,
-                url='http://localhost:8080/api/public/v1/subscriptions/requests')
+                url='http://localhost:8080/api/public/v1/subscriptions/requests?limit=100')
         ])
         self.assertEqual(len(billing_request), 2, msg=None)
 
diff --git a/tests/test_directory.py b/tests/test_directory.py
index 6e367b1..c143488 100644
--- a/tests/test_directory.py
+++ b/tests/test_directory.py
@@ -100,9 +100,8 @@ def test_list_marketplaces(get_mock):
     assert marketplaces[0].id == 'MP-12345'
 
     get_mock.assert_called_with(
-        url='http://localhost:8080/api/public/v1/marketplaces',
+        url='http://localhost:8080/api/public/v1/marketplaces?limit=100',
         headers={'Content-Type': 'application/json', 'Authorization': 'ApiKey XXXX:YYYYY'},
-        params={'limit': 100},
         timeout=300)
 
 
diff --git a/tests/test_models.py b/tests/test_models.py
index 21bb7a5..08e6ab8 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -9,6 +9,7 @@
 import six
 from mock import MagicMock, patch
 
+from connect.config import Config
 from connect.models import Asset, Param, Fulfillment, Item, TierConfig, Configuration, User
 from connect.resources import FulfillmentAutomation
 from .common import Response, load_str
@@ -259,3 +260,27 @@ def test_needs_migration():
     request = requests[0]
     assert isinstance(request, Fulfillment)
     assert request.needs_migration()
+
+
+@patch('requests.get')
+def test_filter_by_products(get_mock):
+    get_mock.return_value = Response(
+        ok=True,
+        text='[]',
+        status_code=200,
+    )
+    config = Config(
+        'http://localhost:8080/api/public/v1',
+        'ApiKey XXXX:YYYY',
+        products=['PRD-000', 'PRD-001'],
+    )
+    FulfillmentAutomation(config=config).list()
+    expected_url = 'http://localhost:8080/api/public/v1/requests?' \
+        'in(asset.product.id,(PRD-000,PRD-001))&eq(status,pending)&limit=1000'
+    get_mock.assert_called_with(
+        url=expected_url,
+        headers={
+            'Content-Type': 'application/json',
+            'Authorization': 'ApiKey XXXX:YYYY'},
+        timeout=300,
+    )
diff --git a/tests/test_product.py b/tests/test_product.py
index 91185bf..ab4407d 100644
--- a/tests/test_product.py
+++ b/tests/test_product.py
@@ -10,6 +10,7 @@
 from mock import Mock, call, patch
 
 from connect.config import Config
+from connect.models import Item
 from connect.resources.product import ProductsResource
 
 from .common import Response, load_json, load_str
@@ -126,5 +127,20 @@ def test_delete_parameter_bad(self):
         assert str(e.value) == 'Invalid ID'
 
 
+class TestItems(unittest.TestCase):
+
+    def setUp(self):
+        self.config = Config(file='tests/config.json')
+
+    def test_items(self):
+        product_resource = ProductsResource(config=self.config)
+        item_resource = product_resource.items('PRD-000')
+        assert item_resource.resource == 'products/PRD-000/items'
+        assert item_resource.model_class == Item
+
+        item_resource = product_resource.items('PRD-001')
+        assert item_resource.resource == 'products/PRD-001/items'
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/tests/test_recurring_asset.py b/tests/test_recurring_asset.py
index a4d0d31..ad3e51b 100644
--- a/tests/test_recurring_asset.py
+++ b/tests/test_recurring_asset.py
@@ -74,9 +74,8 @@ def test_list_recurring_asset_ok(self, get_mock):
         get_mock.assert_has_calls([
             call(
                 headers={'Authorization': 'ApiKey XXXX:YYYYY', 'Content-Type': 'application/json'},
-                params={'limit': 100},
                 timeout=300,
-                url='http://localhost:8080/api/public/v1/subscriptions/assets')
+                url='http://localhost:8080/api/public/v1/subscriptions/assets?limit=100')
         ])
         self.assertEqual(len(recurring_asset), 2, msg=None)
 
diff --git a/tests/test_tier_account_request.py b/tests/test_tier_account_request.py
index 71b9168..dd39b6b 100644
--- a/tests/test_tier_account_request.py
+++ b/tests/test_tier_account_request.py
@@ -77,9 +77,8 @@ def test_list_tier_account_request_ok(self, get_mock):
         get_mock.assert_has_calls([
             call(
                 headers={'Authorization': 'ApiKey XXXX:YYYYY', 'Content-Type': 'application/json'},
-                params={'limit': 100},
                 timeout=300,
-                url='http://localhost:8080/api/public/v1/tier/account-requests')
+                url='http://localhost:8080/api/public/v1/tier/account-requests?limit=100')
         ])
         self.assertEqual(len(tier_account_request), 3, msg=None)
 
diff --git a/tests/test_tier_config_request.py b/tests/test_tier_config_request.py
index 05de778..703e352 100644
--- a/tests/test_tier_config_request.py
+++ b/tests/test_tier_config_request.py
@@ -60,9 +60,8 @@ def test_list_tier_config_request_ok(self, get_mock):
         get_mock.assert_has_calls([
             call(
                 headers={'Authorization': 'ApiKey XXXX:YYYYY', 'Content-Type': 'application/json'},
-                params={'limit': 100},
                 timeout=300,
-                url='http://localhost:8080/api/public/v1/tier/config-requests')
+                url='http://localhost:8080/api/public/v1/tier/config-requests?limit=100')
         ])
         self.assertEqual(len(tier_config_request), 2, msg=None)