ARES HPA System HEB-001 One Side Selector HPA Gear Box 
 
V2 Gearbox with Advanced Electronic Trigger System
Support for All ARES One Side V2 AEG (similar to Her M4 Series)
Some brands may require minor modifications for M4 or M16 models with a single-side selector.
Please ensure compatibility with your AEG before making modifications, as we are not responsible for any loss or damage resulting from such changes.