What are the rules on caps?

Under World Aquatics rules (Part Six, Article 21.4):

• Players must wear their cap at all times in the field of play, the flying substitution area and the exclusion re-entry area.
• Caps have malleable ear protectors in the same colour as the cap, are fastened under the chin, and are numbered on both sides (numbers 10 mm high).
• Colours: the first-listed team wears white (or its team colour) and the second-listed team blue (or its team colour); the two must be easy to tell apart. Goalkeepers wear red.
• Numbers: the starting goalkeeper wears 1; field players wear 2 to 14 (a substitute goalkeeper may wear any number from 2 to 14). You can't change number during a match without the Referee's permission.
• Entering the field of play during play without the correct cap counts as improper entry and gives the other team a penalty throw.

At the SSA U16 National Championships, the first-listed team wears white (light) caps and the second blue (dark), and the organising committee provides the caps.