• Air balanced flow-through piston - First stages with air balanced pistons deliver significantly more air to the second stage than any other first stage, while their performance is totally unaffected by the changing tank pressure. A balanced piston allows the use of lighter and more sensitive components, resulting in ultra fast breathing response, instant delivery of air on demand, and extra high air flow, especially in low tank pressure ranges. The tired diver benefits from a smoother breathing regulator during the ascent or deco stop. Balanced piston first stages are the first choice of demanding sport divers and professionals. A balanced piston performs equally in warm and cold water environments.
• Two opposite high pressure ports - The arrangement of high and low pressure hoses is crucial to diving comfort. Two opposite high pressure ports allow for an individual positioning of the first stage (pointing up or down). This allows the diver to position the gauges either on the right or left side and increases the freedom of movement for head and neck.
• Multiple low pressure ports - For ultimate freedom in the arrangement of low pressure hoses, the MK25 accommodates five HF (high flow) ports on a swiveling turret, which allows for 360 degree swivel of hoses. The MK17 and MK11 feature four stationary low pressure ports, two of them HF. High flow ports deliver about 15% more air than conventional ports.
• DIN/INT first stage configurations - To ensure worldwide compatibility, all SCUBAPRO regulator systems are available in a 200bar INT version as well as 300bar DIN versions.
• Externally adjustable intermediate pressure - Allows authorized SCUBAPRO service technicians to quickly fine tune or make adjustments after maintenance without the need to disassemble the first stage.

Cold Water Diving With SCUBAPRO-Diving conditions can be drastically different, including extreme cold water and outside temperatures, posing the possibility of a regulator "freezing". Therefore, resistance to freezing is imperative for the diver. All SCUBAPRO regulator systems are CE approved for 4300psi cold water diving. Some models go even beyond this super stringent qualification and have successfully been tested in extreme cold diving conditions at less than 36°F. As a specific anti-freezing measure, SCUBAPRO engineers have designed a patented finned cap for both the MK17 and the MK25 first stages for optimal cold water diving. The ribs act as a radiator to increase the surface area of heat transfer from the water to warm up the internal parts that have been drastically cooled down by the gas pressure drop. On the MK17, a dry ambient pressure chamber enhances the resistance to real ice cold water at any depth compared to other dry chamber diaphragm first stages. For cold water diving, SCUBAPRO's second stages feature precision molded carbon fiber and technopolymer valve housing and components. They even exceed the CE cold water norm. In addition, these components contribute to their lightweight features and corrosion resistance.