Edelbrock red roller rockers are made in the USA out of lightweight 7129-grade aluminum. These have a CNC-machined body which is then micro polished and anodized, providing maximal durability. The roller pin, roller tip, and trunnion race are centerless ground, delivering premium quality. A high-quality Torrington needle bearing fulcrum is produced in combination with a roller tip to deliver performance and smooth operation. The full-body design is able to handle springs of up to 1.65" in diameter. Thick-walled adjusting nuts and 4140 steel poly locks come with the rockers.