SRP Professional pistons combine forged piston durability with modern performance technology for an extremely capable forged piston kit that doesn?t break the bank. Forged from 4032 aluminum, SPR Pro pistons experience minimal thermal expansion, making them perfect for a high-performance, reliable engine build from the track to the drag strip. All SRP Pro pistons include premium ring sets, wrist pins and locks. As with all JE Pistons products, SRP pistons are made 100% in the USA.