I have been diving cold water 30-45 dergrees, 100 ft depths for 20 years... For the last 2 years I have been diving with the Atomic’s B1/T2 and the Atomic’s B1/Z2... I have had no free flows and the breathing is so easy even at depths, I notice no change of resistance at all.. Also when not in use the valves and seals are not pressed against any metal while in storage.. So 5 years in the closet and they still work just fine...