ProWin M4 CNC Hop Up Chamber For Marui M4 (AEG)

  • Easy Build & Installation
  • CNC Machined Aluminium
  • Improved Accuracy & Range

Delivers more range and improved accuracy from your Arisoft AEG. Designed for primerally M4 AEGs but may be compatible with other AEGs that use an M4 style hop unit. 

Full description


Not only does the hop unit look good it performs amazingly. With a highly precise and precision tuneable rotary hop wheel you can add micro hop adjustments to any weight BB. An ideal upgrade for any Airsofter and combined with the right FPS you can easily lift up to a 0.36g BB or heavier. Once fully built this hop unit is solid, with zero side hop arm movement your shots are far more consistent in fight path on every shot. We recommend you combine this hop unit with high quality BBs for truly outstanding results! Please note there is no hop rubber or nub included!


  • Incredibly precise and fine hop adjustment
  • No side hop arm wobble
  • Adjustable grub screw hop spacer
  • Easy installation!
  • Improved range and accuracy
  • Everyone who works at Patrol Base loves this hop unit!

Package Includes

  • 1 x CNC Hop Unit
  • 1 x Retention / Seal O-ring
  • 1 x Polymer hop arm
  • 1 x Polymer barrel C-clip
  • 1 x Hop arm pin
  • 1 x Adjustable hop spacer grub screw
  • 1 x Precision adjustable hop wheel & wishbone retention



Internal Part Type
Hop-Up Unit


Colour Wheel Greyscale
Item Colour
Construction Icon
CNC machined Aluminium
Internal Part Construction

Part Specific

Part for Power Source Type
Weapon Platform
M4 / AR-15 / M16

Electric Part Specific

Gearbox Icon
Gearbox Version
V2 Gearbox

Size guide

Parts Fitting

Upgrades and Downgrades should only be undertaken by experienced players, or Airsoft Technicians. Please note, changing any internal parts of a weapon voids its warranty unless done in-house by our staff. 

Please ensure that when fitting parts the part purchased is the correct part, as once a part has been fitted we cannot accept return.

We do know that players love to tinker, so we're here to give you help should you require it, and if needed you can get in touch with our workshop for more help!

Unique Parts

Please note that some parts may be unique to a specific brand of weapon. For example: Parts for an ASG M4A1 may not fit an ICS M4A1.

Parts from the same brand typically have a high chance of fitting, though be warned, some replicas use unique parts, so please ensure the part will fit before you attempt to fit it.

If you require help with fitting any parts feel free to get in touch with us via our Contact Us Page.