With the Apeks Freeflow Control Device (FCD) in-line shutoff fitted to the second stage regulator, a simple sliding action allows the diver to stop the freeflow and continue the dive using a backup or alternatively, the diver can manually control the air flow allowing a safe ascent to the surface. Even the best cold-water regulators can start to dribble gas in near freezing conditions. Inline shut-offs are also commonly used with deco and stage tanks to prevent critical gas loss due to freeflow caused when entering water through surf or off the back of a boat. Inline shut-offs will also stop freeflow caused by strong currents or scooters, which is handy with deco and stage tanks that may be left unattended at decompression and safety stops.

The FCD is easy to install on all second stages with a standard 9/16-18 UNF hose inlet. To operate just push the ribbed slide collar toward the second stage to shut-off or push toward the hose to turn-on gas flow. Slide is made from machined Delrin and the ribbed texture makes it easy to operate even when wearing gloves. The FCD is for use with low pressure only below 200 psi (13.8 bars). Threaded couplings are chromed marine grade brass. The regulator first stage should also have an OPV if the shutoff is used to disable the only pressure relief path.