Skunk2 Valve Keepers for Honda B16, B17, B18, D15, D16, F20B, F20C, F22C, H22A, K20, and K24 VTEC engines are manufactured from chromoly bar stock and CNC machined for a precise fit and finish. Skunk2 Keepers are heat-treated for ultimate strength and black oxide coated for corrosion resistance.