The chains are designed as per API Spec 7F standard and Chinese SY/T5595-97 Standard, which meets and superior than ISO606-94, ANSI.B29.1M-93, BS228-94, JISB1801 standard. Under continuous test and strict product quality inspection, the chains are assured of very well anti-fatigue, anti-friction, anti-abrasion, anti-tension load and impact load as well as the precision mesh of same chains gears. Our roller chains are widely used in petroleum drilling machines and pumping units in the oilfield of China.