Hollis H-02 Piston First Stage - Yoke or DIN RegulatorHollis H 02 Piston First Stage DIN (O2) for Oxygen Rich Diving The Hollis H 02 Piston First Stage is engineered for divers requiring a reliable O2 clean regulator for decompression and stage bottle use. Its DIN connection provides a secure, high pressure fit, while the piston design ensures smooth, consistent performance in oxygen rich applications. Oxygen Ready Performance O2 cleaned for use with high oxygen mixes in technical diving. Secure DIN