WISCO replacement ring set (LK) LK type consists of one top ring and one compression ring: * Top ring: Nodular iron semi-keystone "L" shape. * Compression ring: Chrome-faced high temp steel alloy with ferrox coating. Please note: Only WISCO replacement ring sets may be used on WISCO pistons. The ring type and bore size (mm) is stamped on the dome of the piston. Refer to this information to order the correct replacement rings. Ring styles cannot be interchanged.