 Clearance divers use either compressed air or mixed gas devices.With "oxygen cycle devices" the depth is limited to ; with "compressed air diving devices", which are used also in sport diving, the depth is ; with "mixed gas devices" with trimixes the oxygen portion according to the depth is reduced, thus the possible depth is higher.Since 2002 their compressed air diving devices "FTG" were replaced by computer-controlled mixture rebreathers called "Stealth".