Zeagle 2ND Stage optimizes comfort utilizing a new inhalation diaphragm that provides superior tear strength and improved response time to breathing. An improved exhaust valve ensures dryness and a lower exhalation effort, while a redesigned front cover and inhalation effort control knob use co-molded components that provide the necessary grip, soft touch and ease of use. Co-molded silicone mouthpiece provides a better fit and less jaw fatigue for long term comfort. Durability and long life has also been enhanced using a seat-saving orifice, compliments of Atomic Aquatics, that retracts when not in use, extending the life of the breathing tube seat. The Zirconium-plated inlet tube and heat sink provides superior corrosion resistance, while a redesigned heat sink significantly increases surface area, aiding in the heat exchange necessary to avoid freeze-up.