This listing is for a set of eight (8) +.040 Over size Sealed Power aluminum pistons with pins and a cast piston ring set (Hastings/Perfect Circle/MAHLE) compatible replacements for 1939-53 Ford and Mercury 239ci flathead V-8 engines. P/N (8) 1003NP-40 + 51807-40. Piston specifications are as follows: BORE: 3.2275 (at .040 over size) HEAD TYPE: Crowned head with ring below pin COMPRESSION DISTANCE: 1.519 plus .210 crown PIN STYLE: Floating PIN DIAMETER: .750 RING THICKNESS: 3/32 -3/32 -3/16 -3/16 NOTES: Not factory duplicate; 7.0:1 CR; OE 8BA-6108A; 95-100 HP engines CLICK ON BOX FOR OVER SIZE NEEDED BEFORE ADDING TO CART Pistons and rings Brand Guardian Engine Kits Model Pistons & Rings Exterior Machined Item Weight 20 pounds Manufacturer Sealed Power Perfect Circle Item model number 1003NP 533 Product Dimensions 20 x 10 x 9 inches Manufacturer Part Number 1003NP + 51807 Is Discontinued By Manufacturer No