The A flag, or Alfa flag, is used to represent the alphabetic character A for use in a message between boats. It also means 'I have a diver down; keep well clear at slow speed'. From the International Code of Signals, this long-lasting nautical flag is made from nylon fabric with double-stitched seams, canvas heading and grommets. Measures 2 ft. x 3 ft. Made to order. Allow 4 to 6 weeks for delivery.