You cannot breathe directly out of a scuba tank because of the high pressure. A regulator reduces pressure to safe a level that can be inhaled by the diver. A diving regulator has two parts: the First Stage reduces the tank pressure and connects it to the Second Stage which contains the mouthpiece for breathing
The Hollis DC3 1st Stage Regulator is an over-balanced diaphragm regulator design that provides progressively greater intermediate pressure as depth and gas density increases for superior gas delivery under the most extreme conditions. The diaphragm membrane transmits the pressure changes to the internal mechanism eliminating the need for the surrounding water to enter the intricate mechanism. The benefit of this type of first stage design is that none of the internal parts are exposed to contaminants such as salt, sand, chlorine or pool acids. These environmental contaminants cause corrosion and mineral deposits to form on the internal mechanism deteriorating regulator performance. The standard diaphragm regulator does allow water into the mainspring chamber so that the diaphragm can perform this transmission of pressure changes.
With the DC3 there is a secondary environmental diaphragm membrane that seals off the spring chamber keeping the first stage completely sealed off from the environment adding a second layer of corrosion resistance and the environmental sealing prevents icing of the first stage, allowing the regulator to withstand the rigorous CE standard for cold-water performance.
The first stage has 4 low pressure ports (LP) with 3/8" threads and 1 high pressure port (HP) with 7/16" threads. The DC3 First Stage Regulator is manufactured from marine-grade chrome plated brass and is Nitrox compatible to 40% out of the box. The Regulator weighs 30.7 oz. (870.3 g), is available in a yoke or DIN cylinder connection and comes with a CD owner's manual.
High performance over-balanced first stage provides progressively greater intermediate pressure as depth and gas density increases for superior gas delivery under the most extreme conditions
Designed to withstand the rigorous CE standard for coldwater performance
Environmental sealing prevents internal corrosion, contaminants, and icing of the first stage