Cast from A356 T-6 heat-treated aluminum alloy. Cases are available for 3 1/2in. stock and 3 5/8in. big bore motors for any stroke up to and including 5in. and most stock length connecting rods. Machined to accept an oil filter assembly that mounts on the front of stock motor cases. All races are line-honed and breather cavity is precision-machined to optimize breather timing for maximum oil scavenging. Additional parts include crankcase bolts, washers and nuts, cylinder mounting studs, timing hole plug, magnetic drain plug, assorted breather and oil line fittings, oil pressure switch, oil screen, spring and plug, sprocket shaft Timken bearing assembly and oil seal, pinion shaft main bearing race, cam needle bearing assembly, oil pump drive shaft bushing and installation instructions. Machined for EFI fitment. Made in the USA.