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. This VTC gear is a common upgrade for Accord CL9/CM2 owners who are limited to 25 degrees of movement on their stock VTC. Also a useful service placement for worn teeth on all other K20A/K20Z Type-R engines. As with all genuine Honda parts expect perfect fit and performance every time.