This Piston is made from Forged aluminum and has a flat top, with two valve reliefs. JE Pistons 15 degree LS1 series pistons are designed for stock rods (.945 in. diameter wrist pin) or aftermarket/small block Chevy (.927 in. diameter wrist pin) connecting rods. They have a flat top design that achieves compression ratios suitable for normally aspired applications and are machined for 1.5, 1.5, 3.0mm rings.