Tool mounts to the front of the block, its tabs engage both cam phasers to be held in place so the phaser bolts may be serviced
The ECOTEC engines require the camshafts to be held when removing or installing the cam phaser bolts, or the timing chain may slip and lose its position to the phasers
A pass-through hole on each side allows a socket to be used to remove or install the phaser bolt
