G&G; TR16 MBR 308SR G2 M4 Keymod AEGKeymod Rail SystemQuick Change Spring SystemPower Cut Off w/ Empty G2 MagazineWill Not Shoot Without a Magazine InsertedMicro Speaker to Announce a Low Battery or Motor JamPre-installed G2 MOSFET & Electronic Trigger UnitAdjustable 3 / 5-round BurstElectronic Trigger Unit Size Reduced by 50%G2 Gearbox - 70% more in height & 74% more in thicknessRedesigned Bevel Gear - lower power consumption & less heat generatedThicker Padded Double O-ring Cylinder HeadDouble O-ring Airsoft NozzleAmbidextrous Fire SelectorAmbidextrous Magazine ReleaseAmbidextrous Rear Sling MountBolt Lock - Easier Hop Up AdjustmentAdjustable StockMetal Construction