Competition Cams 1602-16 Ultra Pro Magnum 1.6 Ratio, 3/8" Stud Diameter, Roller Rocker Arm for Small Block Chevrolet Investment cast 8650 chromemoly body and arched, web-like design deliver increased strength and rigidity while reducing moment of inertia Unique black oxide exterior finish helps prevent corrosion, thus increasing durability Optimized retainer and valve spring clearances allow use of most diameter springs, retainers and +.050 inch locks without clearance or fitment issues Feature oversized trunions, precision sorted needle bearings and hardened roller tips