IRS Differential Cover BraceCobra1999-2004 The Cobra IRS Differential cover is cast in aluminum, a material prized for its unique property of strength without the weight of steel or cast iron. Yet aluminum is not as flexible as steel, so when you push your Cobra to the limit in the corners, you may be applying enough force to twist the cover beyond it's ability to flex. By mounting with 6 bolts (supplied) where other designs use 5, the Steeda Autosports Cobra IRS Differential Cover Brace provides 20 more points of attachment, yeilding greater strength and safety. Installation is straightforward using the supplied hardware, and the we have even thoughtfully included a hole to permit easy access to the differential fill plug without the need to remove the brace.