A non-revenue item is something you sell or charge for in store that is not included in your Net Sales. Non-revenue items are typically tax-free items such as charity donations or delivery charges that you need to sell on the POS while keeping the revenue out of your net sales.
You can flag any item as non-revenue by going accessing the item details from the menu in your Silver Back Office.
For non-revenue items to work correctly you need to upgrade your POS app to version 4.3. If you set up a non-revenue item before updating your app you will need to update to 4.3 then perform a data sync.
How to Manually Synchronize with the Back Office.