Smarties in the UK were traditionally sold in cylindrical cardboard tubes, capped with a colourful plastic lid usually having a letter of the alphabet on it. The purpose of this, according to a Rowntree's spokesperson in the 1980s, was for them to be useful as a teaching aid to encourage young children to recognise the letters. Over the last 25 years, Nestlé and Rowntree's have manufactured five billion Smarties lids. Some lids are very rare and are now regarded as collectors' items.