This is the Scubapro MK25 EVO/A700 Scuba Diving RegulatorFeatures: Air balanced piston first stage in a chrome-plated body delivers consistent and effortless airflow, regardless of depth, tank pressure, or breathing rate. Patented XTIS (Extended thermal Insulating system) thermally insulates the inner mechanism from the environment, improving cold-water resistance and delaying ice formation in extreme cold-water conditions without compromising breathing performance. Anti-freeze protection radically increases breathing reliability when diving in the most extreme water temperatures. Two opposing high pressure ports allow the first stage to be positioned either up or down. Four high-flow and one axial super high-flow low pressure ports on a swivel turret maximize hose routing options. External intermediate pressure adjustment enables technicians to fine-tune performance quickly and easily. Rugged full metal second stage case and valve housing (barrel) are able to withstand years of aggressive diving. Metal second stage case construction enables the use of a larger diaphragm inside a compact casing, increasing breathing sensitivity. Air balanced second stage valve smoothes out the inhalation effort when diving at varying depths and supply pressures. Sectional exhaust tee and a first-rate purge help to deliver effortless inhalation and an ease of exhalation that is unmatched. User controls include a diver-adjustable inhalation effort knob and coaxial Venturi-Initiated Vacuum Assist (VIVA) switch. Super-flow hose features an oversized bore that allows more air to flow on each inhalation. With the MK25 EVO/A700 you are guaranteed a reliable, low-effort delivery of air, no matter how hard you&';re breathing, how deep you&';re diving, or what your temperature gauge reads. The MK25 EVO first stage lets you enjoy an ultra-fast breathing response, instant delivery of air on demand, great sensitivity and extra-high airflow, regardless of how cold the water is. The A700 second stage, with its metal casing, screw-down cover, metal valve housing (barrel) and over-molded accents, exhibits a real muscularity in design. Put them together and you get unparalleled breathing performance whether you&';re cruising the balmy waters of the tropics or venturing beneath a polar ice cap. "