Monofins have a maximum size which can be checked by the use of a template while bi-fins must be one of the brands certified (i.e. homologated) by CMAS.
Underwater breathing apparatus is restricted to open circuit scuba using compressed atmospheric air as the breathing gas. The use of oxygen enriched mixtures is forbidden. Cylinders are limited by maximum cylinder pressure rating of 200 bar and a minimum cylinder capacity of 0.4 litres. While there are no requirements for regulators, swimmers appear to be free to modify these to remove any unnecessary parts.
Garments such as swimsuits, swim caps and wetsuits, and the use of logos printed on these garments and the equipment is also subject to the requirements of the international rules.