Maxx Model Hop Up Chamber M4A- PRO RedThis is the newest offering from Maxx Model. The M4A Pro edition is designed for AEGs. 21mm 21. 25mm Nozzles are recommended for this unit. CNC Aluminum Hopup Chamber M4A Pro (with BB Latching System) unit is precisely machined to perform accurately and consistently on Tokyo Marui , including G&G, Kryatc, NOT KWA. Standard M4 M16 AEG series. The Hopup Chamber M4A unit is built with an aluminum Rotary Dial Knob for fine hopup adjustments, the precision

the Hopup Chamber M4A Pro unit is specially designed with a new BB Latching System to prevent BB dropping after removing the magazine

He specializes in custom paint jobs

Real Deal 21mm Nozzle $8

Retro VFC Gearbox

Brushless motors offer more efficiency and performance  than Brushed motors

smooth and consistent trigger pull on version 2 gearboxes

Stable FPS - With airsoft technology advancing

but it sounds unique as well

It does not mean a better version than v2

Which motor should you choose

1x Flat Hop Nub

For details and exceptions please refer to the manual