If you have an item that has not been added to the Backoffice product selection and you would like to add it to the bill, you can use the ADD PRODUCT feature located in the upper right corner.
A new menu page will show up where you can add manually the name, quantity and the price of the product. Here you will have also the options to choose units in which the product is measured (ml, gr and etc.) as well as VAT option. Once you fill in the needed information click on ADD TO BILL.
The new product will be visible on the bill as the following picture:
While this product will be added to the current bill, it will not be added as a permanent item in your Backoffice product selection.