These crimson trace lasergrips fit s&w revolvers and operate using front placement instinctive activation.The smooth black, polymer material provides for snag-free draws and provides ideal grip security for large calibers.The laser activation switch is located in front, making activation "instinctive" when you assume a normal firing grip on the revolver.*note- fits both round and square butt s&w models 10 thru 29, 48, 53, 56, 57, 58, 64 thru 68, 242, 329, 396, 520, 547, 581, 586, 610, 617, 624, 625, 627, 629, 648, 657, 686 and 696.Does not fit k frame scandium revolvers, does not fit with target hammer.Power Switch: Pressure PadWavelength: 633nMDot Size: .50" @ 50 ydsPower: 5mWRange: 50 ftWeight: