Simulates the installed length of your coil-overs, It fits 1/2″ or 5/8″ coil-over mounts CAST RUBBER ISSUE KNOWN. USE 582SM3000 REPLACEMENT RUBBER INSERTS., Available from 9″ through 17″ minimum installed length, Adjustment of at least 1″ longer is possible, Each rod end includes sleeves for both 1/2″ and 5/8″ diameter bolts.