From their cold-wound chrome silicon wire to their special protective coating, AFCO Racing AFCOIL coil-over springs are built to win. Their chrome silicon wire construction gives the springs superior tensile strength to chrome vanadium steel springs. The springs come with double-ground ends for improved squareness (to within 1 degree) and a protective coating for longer life. AFCO even guarantees that the springs will remain within two percent of their original free height for as long as you own them!