Dayco No Slack Heavy Duty Idler/Tensioner Pulley is designed to replace idler and tensioner pulleys for serpentine drives in heavy duty diesel engine applications. This pulley is machined from high strength steel material to afford wear resistance under harsh environments; and, it features double pressed-in bearings to provide long bearing life despite the shock loads experienced in diesel engine applications. The performance demands of original equipment manufacturers of over-the-road trucking and off-road equipment require a built for punishment heavy duty construction, that is why they specify Dayco No Slack Heavy Duty pulleys. Product Features:This pulley is machined from high strength steel materialFeatures double pressed-in bearings to provide long bearing life despite the shock loads experienced in diesel engine applicationsWear resistant materials made to operate under harsh environmentsMeets or exceeds OE quality