Jims Engine Rotator Tool For Harley Big Twin 1955-2006 Features: Rotates flywheel/piston assembly with engine still in frame or on a bench Built with a long socket design, making it easier to use without a 1/2 drive extension on your 1/2 driver Helps with pushrod adjustments, for checking piston or valve clearances or to hold flywheel assembly from rotating when torque is applied to the cam drive sprockets bolts on Twin Cam or pinion shaft nut on single cam models Made in USA Note: Not for use with an air or electric impact wrench this tool is only guaranteed for use with hand drivers.