This mess undress is optional wear in the evenings for dining by all senior rates and warrant officers. It is worn with a black cummerbund and miniature medals. The cut of the jacket is different from that worn by officers: it is double breasted, but features a shawl collar and only four buttons instead of six. Trade badges and other non-substantive badges are not worn on the mess jacket, but cuff buttons and substantive rate badges are. This is worn with plain blue mess trousers and (optionally) the peaked cap. Those senior ratings who have not applied for mess dress for 2B dress may instead wear 1C dress with a black bow tie substituted for the black straight tie.