Features:Totally internal-cannot be knocked out of alignment No permanent modification to gun-remove it anytime No need to change holster or give up your rail flashlight Compatible with your favorite grips and aftermarket accessories Drops into place, replaces original recoil spring guide Ambidextrous switch in custom take-down lever Deliberate on/off activation-no squeezing the grip, no shaking Pulsating beam for increased visibility Factory aligned (1911 models are also user adjustable for fine tuning) Quality assurance includes live test firing