(No trades i onley ship to the lower 48 states) Fully polished "Silver Edge" gearbox increasea overall efficiency by up to 15% from standard gearbox designs Made from high strength zinc alloy; reinforced in key areas for longevity 8mm stainless steel bearings provide smooth travel for the steel gear set Ported cylinder optimized for carbine length inner barrels (~363mm) Integrated "quick spring release" function for easy spring change Advanced S.D.U. chipset to manage shot-to-shot amperage draw (gearbox only pulls 11amps at ~380 FPS) for improved consistency, performance, and instantaneous trigger response making this one of the most efficient stock gearboxes on the market Wired to the rear with a Deans style T-plug Ambidextrous cams and gears included