series: 25H,420,428,428H,520,530,530H etc. we are one professional chain factory ,producing both standard roller chains and nonstandard chains.majior product is :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 etc.Comply with the standard of ANSI,ISO,DIN,BSetc.Quality can be guaranteed! ...