Apeks Xtx 40 Octopus. XTX40 OCTOPUSNew XTX pneumatically balanced second stage has leftright reversibility and a Diver Changeable Exhaust DCE system. This system gives the diver the ability to change from a large exhaust tee to a smaller exhaust tee. The large tee provides the best exhaust bubble dispersion the smaller tee is lighter weight and compact. Both exhaust tees are included with the regulator.