ATOMIC M1 REGULATOR 1ST & 2ND STAGE DIN/YOKE (READY TO DIVE). This first and second stage regulator with safe second connection hose....... is ready for your next dive. I recently had it completely rebuilt by a licensed technician at a local dive shop. It has not been used since the rebuild. M1 regulators are nitrox and cold water ready with stainless steel working parts. Reviews for this regulator speak for themselves. Happy Diving!!!!!! Condition is Used.