This billet idler pulley is identical to the Metco Motorsports MIP-100 idler pulley except that it is 10mm smaller in size to match the OEM idler pulleys. The larger 100mm diameter of the MIP-100 is designed for use in auxiliary idler applications where a smaller than stock supercharger pulley is installed. This 90mm pulley is CNC-machined from billet aluminum and black hard-coat anodized on the belt surface and back side for long-lasting surface protection. A heavy-duty bearing is precision-fit into the center bore, and a snap-ring ensures everything stays in place. This 90mm idler pulley can be used as a heavy-duty replacement for the two idler pulleys on the factory crossover bracket, and as a heavy-duty replacement for the factory crank idler on the 2003-2004 Mustang Cobra. The kit includes a billet bearing cover and a stainless steel socket head fastener to mount this idler pulley to the original or Metco Motorsports pulley mount.