These are the most advanced, state of the art, pushrod cover sets available. Each piece of aircraft aluminum is CNC machined to our patented designed shape and dimensions for a precise fit. These have a polished finish. The center coupler expands the top and bottom tubes. A compression O ring located inside the coupler, holds the pushrod covers firmly in place. Neoprene seals and O Rings ensure no leaks as they expand and contract with engine heat. Will not work with taperlite or large O.D. pushrods. Manufacturer