HONDA VTC Actuator. This cam gear sits at the end of the intake camshaft allowing a set degree of cam advance/retard. This is what differentiates later i-VTEC engines to the earlier traditional style VTEC system. While the ECU controls the amount of movement, it's mechanically limited by the range on the gear itself, 50 degrees is the maximum amount of movement from any stock actuator. As with all genuine Honda parts expect perfect fit and performance every time.