In addition to protection and communication, the packaging has a function in defining the quantity. A packaging unit which is either too large or too small may not be attractive to the consumer. He or she will consciously choose a certain quantity and a certain type of packaging. By offering various kinds of  'convenience packaging’ the manufacturer can fulfil the broad range of consumer requirements. The packaging sizes available in supermarkets, for instance, will differ from those available at petrol stations. Manufacturers put together series of packaging units to meet different needs.