Compliment slips are often produced as a repetition of a letterhead but sized 210x105 or1/3 A4 .

Depending upon the quantities involved It is often more economical to produce these at the same time as the letterhead by using the same printing plates to print three compliment slips and one letterhead to view.

A print  run of five hundred would then give five hundred letterheads and fifteen hundred for compliments slips, saving a set of plates, and another print run therefore reducing costs!