Features and Benefits: 40 piece set covers taps and dies from 3mm to 12mm ; Ratcheting "T" Wrench provides a 5 degree ratcheting arc for tapping engine blocks; Replaces need for slower existing tap and die wrenches; Reversible lever allows quick change from forward to reverse eliminates hand over hand turning; Twist Lock Guide System keeps dies centered while cutting threads.; GearWrench Tap and Die Set includes Index holders for taps. All taps and dies lock in place. Features comfort shaped grips.