This is a KMC "Drop Buster" chain - stretchproof chain with mushroom rivets and thicker side plates. * 1/2" X 1/8 * Copper (not as light as the stuff coming out of Japan - this looks like a one or two year old American penny) * Model number is Z510HX * 113 links * Comes with built in offset link and master link (both of which are NICKEL - not the copper finish) * Great stretchproof chain for any single speed application (BMX, Fixie, cruiser, etc.)