... 2.high clamp, redundant reliability and stability. BT40 keyless drill chuckBT40-13MM 1-13 Application:1.wearing parts quenching ... Has from the tight function, clamps the drill bit gently then, in the drill hole along with the pitch of strand increases, ... spindleFeatures:3 times better clamping capacity , comparingTo keyed drill chuckThe drill bit won't be loosen or falling offTwice precision ...