All of Apeks' XTX regulators feature a Reversible Venturi System (RVS), which allows regs to be converted from a right-handed hose configuration to a left-handed one. Moreover, the XTX range of regs incorporates the Diver Changeable Exhausts system (DCE), which gives divers the ability to switch between a small exhaust tee and a large exhaust tee. (A wider tee yields less bubble interference,  especially useful for underwater photographers.) Apeks makes several of these "customizable" XTX regs, from the hardy XTX200, suitable for cold-water diving, down to the XTX20, more appropriate for warm-water diving.

[Via X-Ray Mag]