Severe duty driving stresses the Original Equipment (OE) tensioner and alternator decoupler pulley (ADP) - leading to noise complaints and drive system failure. The ADP takes all the abuse. Once the ADP fails, it can lead to failure of the other components. Therefore, it's recommended to replace the belt, tensioner and ADP at the same time.The 38185K Kit offers the parts needed to completely service the accessory drive, including the Alternator Decoupler Pulley (ADP). Often times, replacing the ADP will negate the need to replace an expensive alternator.Kit includes a Specially Constructed Belt, OE Improved (OE+) Tensioner and an OE Exact (OEX) Alternator Decoupler Pulley to ensure enhanced durability and less costly repairs.Gates - Driven By Possibility.