Unit price information in supermarkets
Unit price information printed on supermarket shelf labels (price tickets) illustrates the quantity of product by a unit of measure (price per 100 g, price per 100 ml). Unit pricing was originally designed as a device to enable customers to make comparisons between grocery products of different sizes and brand, thereby enabling informed purchase decisions.
Source: Wikipedia — Unit price information in supermarkets (CC BY-SA 4.0)