The 14-1/2" 21mm/24mm Wrench can be Used to Move Hard-to-Reach and Often Rusty OEM Cams on 1999 and Newer GM 1/2 and 3/4 Ton Vehicles with Coil Spring Front Suspensions. The kit includes a cam adjusting holding tool to adjust the upper control arm cams found on Chevrolet® and GMC® vehicles. The holding tool surrounds the entire perimeter of each cam to provide a no-slip work area when moving the hard-to-reach and often rusty OEM cams. The 14-1/2" 21mm/24mm wrench can be conveniently used from the bottom side of the vehicle instead of reaching through the wheel well which saves technicians time.