Code flags used by ships and yachts are available in four sizes.
In spite of modern methods of communication, International Signal Flags and Pennants, commonly known as Code Flags continue to be used. A set comprises 26  flags (A-Z) and 14 pennants (10 numerals, three substitutes and an answering  pennant). Sets or individual flags may be ordered in the sizes:
60 x 40cm, 75 x 60cm, 115 x 90cm and 180 x 120cm. 
The most popular sizes are 60x40cm for smaller craft and 180x12cm for large ships.