... meet or exceed DIN, ANSI,ISO,BS,JS standard, and stand up to the toughest working environment. Our Precision roller chain ... exceed DIN, ANSI,ISO,BS,JS standard, and our chains stand up to the toughest working environments with years of trouble ... with surface and core 39-45HRCShot peening per the spec 4-Strands B Series 12B Roller Chain Manufacturer