Locks flywheel in place when removing harmonic balancer on 6.6L Duramax Engines with Allison automatic transmissions Saves time by locking the flywheel at the transmission instead of having to remove the starter for water pump replacement On 2500 and 3500 pickups, remove metal spring-loaded inspection plate on the bottom of the transmission For more information check the main Lisle tool- 22100 Replacement part for Lisle tool- 22100