With Full Shelf, you can quickly create purchase orders and send them to your suppliers, either by downloading a PDF file, or emailing a link. The app will automatically restock your inventory quantity, when a PO is received, saving you time in the process. The app includes a "Supplier SKU" field, in case you need to differentiate from your own SKUs. Also, it allows creating a PO from a regular Shopify Order, and request a supplier to ship tot the customer directly.