This compact first stage regulator by Apeks has been embraced by the technical diving community worldwide. This DS4 first stage boasts an overbalanced, diaphragm design which allows the medium pressure gas within the hose to increase at a rate faster than the ambient as the diver descends. This makes for a superior performance at depth. Additionally, an environmental dry system keeps the main spring chamber free of water, thus preventing ice buildup and keeping silt and contamination from seeping in.