The key figure is torque, measured in either foot pounds (ft. lbs.) or inch pounds (in. lbs). Higher torque generally equates to more consistent performance for longer. The speed of the hammer we use it for emergency lockout action will also be given, in BPM (blows per minute) or sometimes IPM (impacts per minute). Motor speed (in rpm) is also included, though less important in an impact driver than for a standard drill.