Formal trousers

Morning dress with formal striped trousers (Fashion, 1901)

Formal trousers (in British cashmere stripes or, in American slang and at Eton College, spongebags) are formal striped trousers worn with morning dress and semi-formal daywear. They have a muted design in stripes of black, silver, white and charcoal grey in various combinations and are made from heavy wool.

'Cashmere stripe' refers to the actual name of the stripe pattern and not the fabric content. Similarly, 'spongebags' is the slang term because the pattern is similar to traditional sponge-bags. The pattern is made up of many different lines of different shades of blacks, greys and such grouped together to form bold distinctive stripes and are not to be confused with pinstripe or chalkstripe which are formed of single thin lines spaced equally apart.

Formal trousers also come in other patterns such as houndstooth check or plaids but these are not referred to as 'cashmere stripe'.

Typically, formal trousers are made to be worn with braces with a fishtail back and have pleats. They do not have turn-ups.