Item Variant Details.
The variants tab on the item details screen allows you to setup variants such as size and colour of the main item. This saves you time and effort by not having to setup an individual item for each size/colour that you sell.

If you select the main item on the till screen then a new window pops up allowing you to select the required variant for the sale.

If you select the main item on the till screen then a new window pops up allowing you to select the required variant for the sale.