This lightweight aluminum water pump pulley drives your water pump 6% slower than stock to minimize parasitic loss and improve acceleration. By spinning the water pump more slowly you also decrease cavitation at high RPM and improve cooling.
All MWR pulleys are made of lightweight 6061 aluminum with a hard anodized coating. This results is an ultra light part with the same surface hardness as hardened steel. Weight is 247g compared with 325g for the stock pulley.