diff --git a/code/Heystack/Subsystem/Ecommerce/Purchasable/Interfaces/PurchasableHolderInterface.php b/code/Heystack/Subsystem/Ecommerce/Purchasable/Interfaces/PurchasableHolderInterface.php
index <HASH>..<HASH> 100644
--- a/code/Heystack/Subsystem/Ecommerce/Purchasable/Interfaces/PurchasableHolderInterface.php
+++ b/code/Heystack/Subsystem/Ecommerce/Purchasable/Interfaces/PurchasableHolderInterface.php
@@ -62,6 +62,13 @@ interface PurchasableHolderInterface extends TransactionModifierInterface
     public function getPurchasable(IdentifierInterface $identifier);
 
     /**
+     * Retrieves a purchasable from the implementing class' internal cache of
+     * purchasables using the Primary string on the Identifier object
+     * @param \Heystack\Subsystem\Core\Identifier\IdentifierInterface $identifier
+     */
+    public function getPurchasableByPrimaryIdentifier(IdentifierInterface $identifier);
+
+    /**
      * Removes a purchasable from the implementing class' internal cache of
      * purchasables
      * @param \Heystack\Subsystem\Core\Identifier\IdentifierInterface $identifier
FEATURE: Added getPurchasableByPrimaryIdentifier() so that we can retrieve the purchasable just using a part of the identifier (Primary)