It is made from heat treated H-13 tool steel that has been triple tempered and salt bath nitrided for a smooth yet very durable finish. The threads are rolled and the ball has a shape design that is compatible with a pushrod cup depth that exceeds its own radius.
Please specify 5/16", 3/8" or 13/32" ball as well as no oil, oiling hole thru the center, or pressure feed oiling from the drop down menu. Rocker arm adjusters are sold each.
RBS also carries the twelve point rocker arm adjusting nuts if the racer needs.