The Gates DriveAlign Idler Pulleys are designed for both imported and domestic automotive use. The steel or thermoplastic construction of the idler pulleys provides high durability for longevity. The bearing meets or exceeds OE and is designed for application, both specific speed and load requirements. The idler pulley is reliable in operation under severe conditions. The serpentine belt is part of your vehicle's accessory belt drive system, which is also known as ABDS. Along with the tensioner and pulleys, the belts ensure that the performance of the accessories like the alternator, water pump and A/C compressor are optimal. If your belt exhibits one or more of these symptoms, it may need to be replaced: Rubber loss Glazing Pilling Abrasion Cracking Please view the online parts guide or speak to one of our friendly team members for assistance with part numbers.