This item is for a bundled set of (8) .040 over size or 4.040 bore diameter hypereutectic flat top pistons with 4 valve reliefs compatible with 1968-85 Chevy 350 cid (5.7L) small block V-8 engines. These pistons can be used as a performance upgrade in engines originally equipped with dish top pistons without modifications. These pistons are designed for either press fitted or floated connecting rods. Lock rings are not inclided and must be purchased separately. Piston specifications: Bore: 4.040 inch Stroke: 3.480 in. (stock) Connecting Rod Length: 5.700 in. (stock); rods Not included Piston Top Style: Flat top with 4-valve reliefs Compression Height: 1.548 in. Piston Material: Hypereutectic aluminum Wrist Pin Diameter: .927 in.; pins included Wrist Pin Style: Press-fit or floating; pin clips Not included Ring Land Sizes: 5/64-5/64-3/16 (oil ring); Rings Not included Notes: DurOshield coated skirts; These can be free floating but locks must be purchased separately. Usage: Stock, Street and mild strip RPM Range: Idle - 6,000 Compression Ratio (approximate): 10.2:1 w/58cc; 9.6:1 w/64cc; 8.5:1 w/76cc