Cometic EST Complete Engine Gasket Set For Harley Sportster 883 EST (Extreme Sealing Technology) kits are made for any builder who demands the best and appreciates the long-term value for his/her dollar. Features: Kit contains MLS head gaskets, steel Viton coated base gaskets, blue Viton valve stem seals and AFM material Race style exhaust gasket that won't fray into the port One-piece Evolution rocker box base gasket which is made from a single layer of .020 thick embossed Viton coated steel Replaces OEM 17026-86A