Srp sb-chevy high compression forged pistons are smooth flowing symmetrical dome for excellent flame propagation. Dome requires no de-burring or preparation. Designed for use in All common 23 degree heads. Non-silicon alloy for superior strength in high cylinder pressure applications. Symmetrical dome and valve reliefs for universal installation. .927'' x 2.750'' x .150'' straight wall carbon steel wristpin (130G) included. 1/16, 1/16, 3/16'' ring grooves.