Each Crankshaft Socket is specifically sized for a particular engine make and crankshaft nose dimensions. When in place a Crank Socket will engage with the woodruff keyway that should be installed in the machined slot in the nose of the crankshaft. A Ratchet Wrench or Breaker Bar (usually a 1/2" drive fitting) can be engaged into the square slot of the Crank Socket and be used to rotate the crankshaft.