Forged high compression Wiseco piston kit. 9.5:1 compression ration (stock is around 8:1). Includes wrist pins circlips and Hastings rings. Note: These Wiseco pistons will fit stock style Hastings rings with 1.2mm (0.047") top & middle ringlands and a 4.75mm oil ring. 79-84 1340 Shovelhead (NU)