CNC ALUMINUM HOPUP CHAMBER MXWCNC Aluminum Hopup Chamber MXW unit is precisely machined to perform accurately and consistently on HPA MTW Milspec, Forged, Billet and MTW 9 series. The Hopup Chamber MXW unit is built with an aluminum Rotary Dial Knob for fine hopup adjustments, the precision Hopup Lever and 4mm Bucking Nubs (6mm Bucking Nubs are optional) to perform best with R Hop and Standard Hop to keep the BB shooting accurately and consistently on every single shot. The Hopup