material :40Mn bluing or shot peening, we are one professional chain factory ,producing both standard roller chains and nonstandard chains.majior ... :A and B series roller chain,straight side roller chain,H series of roller chain, motocycle chain ,other roller chain .Zinc-plated,Nickel-plated,Docromet-plated ... ANSI,ISO,DIN,BSetc.Quality can be guaranteed! sharp top chain