Description: Airsoft Systems - ASCU2 Gen 4+ for Gearbox V2 ASCU 2 Control Unit Gen 4 gearbox with a switch base Gearbox V2. Difference from Gen3 : 1. New MosFet transistors with 16 times less resistance, resulting in to faster cycle, better active brake, more shots per battery charge and less heat. 2. New very strong trigger switch. 3. New reinforced design with full polymer encasing. 4. Better short-circuit protection. 5. Easier installation. 6. Updated software with easier programming (accidental hop-up program activation is impossible). 7. Improved cut-off lever. 8. Improved selector plate. 9. Fits all standard and reinforced version 2 gearboxes. 10. 3 year world wide warranty.