These upgrade aluminum clamping wheel hexes fit:

That's a weight savings of 9

Standard Programmable Digital Circuit for More Holding Power

Body material : ABS Plastic

5*8mm Allen bolts x 12

HPI Racing - Wheelie Bar, for the E-Firestorm RGR4505 These upgrade aluminum clamping wheelMaximize your fun with a wheelie bar set designed specifically for the E Firestorm! This Wheelie Bar it will stop your E Firestorm from flipping over when using full throttle, and it will allow you to pull perfect wheelies every time. This set includes everything you need to assemble and install a unique wheelie bar on the rear of your E Firestorm. Replaces the motor guard with a modified version that includes mounting points for the wheelie bar.