This is an optional RPM Gear Cover The BK2 & MF2 editions of the XXX and XXX-T use a different transmission that will not allow the use of RPM's standard XXX version gear cover. The stock lexan version of the BK2 & MF2 gear cover does not seal off the gear case from debris very well and is prone to cracking around the screw holes simply by installing it on the vehicle. RPM molded Gear Covers are the best and only alternative over the flimsy stock versions.RPM Gear Covers are molded from high strength nylon materials, not vacuum formed lexan that easily cracks and breaks. Since RPM Gear Covers are molded to the strictest tolerances, there is absolutely no cutting or fitting required to get the cover to fit on the vehicle. RPM includes three 4-40 x ½” socket head cap screws in the package which allows easy installation using a 3/32” Allen or ball driver. RPM has also added in a thin web of material at the top of the mounting hole so the mounting screws will stay with the RPM Gear Cover when it has been removed from the vehicle - no more lost mounting screws! RPM Gear Covers also come with a large soft plug that protects the slipper access hole from dirt & debris while allowing easy access to the slipper adjustment nut.