We can use the eStore (Cart) module to track and sell products for your organization. We many run into a situation, though, where we need to track sizes for the same type of Item. For example, your organization may sell shirts and have a limited quantity of each size.
In order to track the quantity for each size, we need to create a different Item for each size. We should include the size in the Item Name so that we can easily identify which size correlates to the specific Item. The steps to create a new Item are available at How to add a new Cart Item.