REBUILD KIT, CARBURETOR, MIKUNI BST33. Full list of parts contained in the kit: Japanese-made float needle, needle seat o-ring, cold start enrichment feed pipe o-ring, genuine Mikuni float bowl gasket, Japanese-made fuel screw o-ring, slide guide o-ring, two felt throttle shaft seals, two stainless steel flat hexalobular throttle blade screws and instructions. NBR vs. FKM o-rings