Specifically designed for circle track and road racing applications, where the rules call for a 9.5:1 piston. Standard 350 Series accepts 1/16, 1/16, 3/16 rings. Includes: Pin #927-2750-15-51S (130g) Double Spiro Locks # 927-042-CS. Bore: 4.030 Stroke: 3.500 Rod: 5.700 Deck: 9.000 Price per piston.