Ronstan's Bullseye with a Stainless Steel Liner is molded from high load-bearing Nylon resin and has a stainless steel liner to provide maximum wear resistance in redirecting line. It works especially well with high-tech line. This deadeye's aperture is 5/8 in. (16mm). It measures 1 9/16 in.long x 1 5/16 in. high x 3/4 in. wide (40mm x 33mm x 19mm).