Sometimes goods are sold by weight instead of by unit. Think for example about groceries or fine Belgian chocolate. Most POS systems have two ways of working with weighing scales or balances: sometimes the scale is directly connected to the point of sale through a serial cable and in other cases the scale produces a barcode that can be read at the POS.
When purchasing a scale you have to verify that the scale is suited for the weight range of your items. There are scales for small items up to one kilo, but also scales that can be used for heavy items weighing for example 100 kg.
Usually you have to specify in the item file that a particular item has to be sold by weight. When selling the item, the EPOS system will prompt you to place the item on the balance and will wait for input. Manufacturers of POS scales include Bizerba, Campesa, Mobba and Wedderburn.