These Scorpion Racing Products SCP1000 SBC Roller Rocker Arms feature a 1.5 Ratio and fit 3/8 Studs. These Race Series rocker arms are designed for 265-400 inch Small Block Chevy engines, and are CNC machined from 7000 Series Aerospace-Grade aluminum for maximum strength and durability! Scorpion SCP1000 Race Series SBC Roller Rocker Arms Feature: For 265-400 cubic inch Small Block Chevy engines Will handle .950” lift & 950 lbs. max open spring pressure Clear 1.625” valve springs 1.6” fulcrum width Full body design Needle Bearing Fulcrum and Roller Tip Centerless Ground Trunnion, Pin & Roller Blue Anodized for additional protection and durability Burr-Free Thru Hole in Trunnion Large Machined Seat Thick-Walled Adjusting Nut Pedestals Machined from Solid Steel Black Oxide Coated Steel Parts Lifetime Warranty 100% Made in the USA! Made for the most demanding street and racing applications, Scorpion’s top quality Race Series Roller Rocker Arms provide superior performance and more horsepower!