For optimal efficiency, BIG BORE® BB-EXL-SC2G utilizes spring clamping and pneumatic unclamping, and has step mode for partial opening and clamping when shimming. As self-centering chuck, unit provides open and clamp time of less than 3 seconds. Optional stroke control monitors both pressure and stroke to ensure that pipes stay in place and won’t allow jaw to move if pressure is too low. Proofline® sealed, chuck has permanent grease lubrication to retain constant grip force.