Great for High Performance or Just As An Upgrade! Serpentine Drive Belts have become the primary system of driving accessories on all modern vehicles, with more engine pulleys needed to hold tension, reduce slippage and increase mechanical efficiency. Many of these pulleys are manufactured from moulded plastic to reduce cost, however plastic offers limited durability when exposed to abrasive dirt, heat or when excessive Belt tension is applied. Nuline engine pulleys are manufactured from metal for far greater strength and wear resistance when exposed to environmental factors. All ball bearings are manufactured from high quality bearing steel using a nylon cage and using ETK grease for quiet running and maximum bearing life. In independent testing by a NATA accredited laboratory Nuline bearings equalled or exceed the values by OEM bearings in all areas. Using Nuline engine pulleys will assist performance tight tolerances to ensure smooth operation and extended life.