This regulator comes O2 clean for your oxygen needs. The DIN first stage operates with by piston and has 1 high pressure and 4 low pressure ports. The second stage Has a green purge cover with a chrome finished brass ring. The 40" green flex hose allows for a variety of hose configurations, whether it is being used on a stage bottle or being stored onboard. Components configured with Viton O-rings and Christo-Lube.