External/Affiliate products are not held in your store inventory but customers can use your store to purchase these items. This would apply where you are acting as an agent for a manufacturer, wholesaler or other entity.
Choose ‘External/Affiliate’ from the product type drop down. This will remove unnecessary tabs such as tax and inventory and insert a new product URL field. This is the destination at which users can purchase the product. Rather than add to cart buttons, they will see a read more button directing them to this URL.