G&G have shared details of their rotary-style hop up:
Put Your Shots on Target With an Upgraded Hop Up Unit
Rotary Hop Up
G&G
Update your AEG with a rotary-style hop-up chamber. The G&G Rotary-Style Hop Up is made from high-quality reinforced polymer and is compatible with all M4/M16 AEGs. Make faster, more precise adjustments on and off the battlefield. Now available with your local G&G Authorized Dealer.
