These are a high quality M1 tool steel USA made polished flat tappet lifter for the Kohler Command engine. They will work with horizontal and vertical style engines. We recommend using them on cams that have been hard surfaced overlay. Our Stomper cams, other vendors weldup and regrind cams are good examples of this. They are sold EACH so if you need a set of 4 then add 4 to your cart.