... standard, and stand up to the toughest working environment. Our A Series Roller Chain meet or exceed DIN, ANSI,ISO,BS,JS ... , looking forward to establish win-win business relations with you in the near future.General Standard for Roller Chain:ROLLERSolid RollerMaterial ... and core 39-45HRCShot peening per the spec 5-Strands A Series Roller Chain