If you sell variations of the same item, such as a shirt that comes in different sizes and colors, master stock items will make your inventory easier to manage. Master stock items work in conjunction with substock items, with the master item functioning like a heading for the sub items. To add an item of inventory into Sage 50, open the Inventory & Services Navigation Center in Sage 50. Click the Inventory Items icon and select New Inventory Item from the drop down list provided. This displays the Maintain Inventory Items window where you can enter the details of the inventory item into Sage 50.