The EMPI Front Caster Shims are made from 6061 T-6 Aluminum and are designed to adjust the caster angle settings on your front suspension back to original to balance high speed stability, cornering effectiveness and steering effort. Check your current Caster Angle as there are 4 sizes to allow an alternative to stacking shims with extreme lowered front ends. Also available are longer front end mounting bolts to accommodate the shim thickness. Sold in Pairs