CNC Aluminum Hopup Chamber M4P Pro (with BB Latching System) unit is precisely machined to perform accurately and consistently with HPA PolarStar Engines on standard M4/M16 platform. The Hopup Chamber M4P 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 Chamber M4P unit is designed to accept the HPA PolarStar Engine M4 nozzle length, and fully compatible with most aftermarket soft and hard rubber buckings without losing FPS or dropping BB during use.

The Hopup Chamber M4P unit is wisely equipped with an interchangeable Inlet Adaptor OD11mm to ensure the hopup unit is inserted exactly in the center of the 11mm inner bore HPA Engine nozzle outlet without wobbling. (Inlet Adaptor OD11.5mm and OD12mm are optional)

Also mounted the removable CNC Brass Side Wings to slide smoothly into the outer barrel slots, and included an advanced CNC Delrin Locking C-Clip to hold the inner barrel tight in place without wobbling and twisting.

More than that, the Hopup Chamber M4P Pro unit is specially designed with a new BB Latching System to prevent BB dropping after removing the magazine. The Latching Arm can also be manually pressed to release the remaining BB from inside the hopup chamber.

***The Dual UV LED Tracer Module is an add-on option to glow BB in the dark. Operating Voltage from 7VDC - 15VDC (2-4 cells LiPo, 6-13 cells NiCad). (Sold separately)

***Test results: FPS might be increased from 10FPS to 30FPS over the stock setup. Please check your FPS!