Roger Clark Motorsport Alloy/Steel Adjustable Vernier Exhaust Cam Gear Pulley SetRCM Adjustable Vernier Pulleys are a valuable asset to any high performance engine allowing adjustment for exact valve timing to ensure the combustion process is as efficient as possible. Given the important role of the camshaft pulleys, strength, durability, accuracy and quality are all important factors when producing such components. The outer toothed wheel of our vernier pulleys is manufactured from 7075 T6 Alloy which is a "Class 1 Type A