ANSI Premium Precision Roller Chain #617107R91 features:• Wide waist link plates for added fatigue strength: Link plates of 60H and larger are manufactured with a wide waist. For improved stress distribution, pitch holes are ballized by forcing a tungsten carbide ball through the pitch holes, which increases the bearing area and press fits, improving fatigue life and working loads• Precision hole quality increases fatigue resistance and pin retention: After heat treatment on sizes 80 and up, residual compressive stresses are imparted to link plate pitch holes through ballizing. This provides optimum bearing contact among mating pins, bushings and link plates. The ballized pitch hole increases fatigue strength and pin retention• Solid (seamless) bushings increase wear life: Optimum concentricity of a solid bushing increases the wear life of the chain• Smooth rotation with solid rollers: The solid roller allows for smooth rotation on the bushing, reducing the impact load as the chain engages the sprocket tooth• Shot peened roller and link plates: Roller and link plates are shot peened for greater fatigue strength• Factory preloaded to withstand shock loads: We preload our chain so that applications can withstand shock loads up to 50% of the chain's minimum ultimate tensile strength without premature elongation• Special hook cotter: A full hardened hook cotter provides greater link plate support and up to twice the shear strength of conventional short split cotters• Pre-lubricated/hot-dip lubrication for improved wear life: After final assembly, roller chains are hot-dipped in a proprietary lubricant designed to penetrate and fully coat the bearing surface between pin and bushing. This process ensures that all the load-bearing surfaces are initially protected from metal-to-metal contact, improving the wear life of the chain