 In the RAF mess dress, officially designated Number 5 dress, is worn at formal evening functions.All regular officers possess mess dress whereas warrant officers and senior non-commissioned officers wear mess dress if they choose to purchase it.The current mess dress for men consists of a high waisted blue-grey single-breasted jacket fastened at the front by a single link of two RAF buttons connected by a link clip, white marcella shirt, bow tie, waistcoat or cummerbund and blue-grey trousers.