High performance with free flow control.The economical Envoy II octopus is the same internally as the ZX 2nd stage, but does not have the adjustment knob or the heat exchanger. The Envoy II Octopus has a Venturi Control Lever that allows the diver to set the octopus 2nd stage in the Pre-Dive position until needed.This is very important in Octopus regulators, since the Pre-Dive position is much more resistant to Venturi-Free-flows that can sometimes result in significant air-loss during a dive. The Envoy II Octopus comes with a Yellow cover and 36" hose."