The Pro-Line X-Maxx HD Performance 24mm 1/5 Axle Conversion is made specifically for the X-MAXX monster truck. This optional heavy-duty machined aluminum Axle conversion will allow you to run any 1/5 scale 24mm wheels and tires already available, including Pro-Line's Masher X HP Tires without needing adapter washers! This conversion is also a massive durability upgrade over stock because it replaces the plastic hexes with machined aluminum and has a much bigger axle diameter. The Performance HD 1/5 Axle Conversion comes pre-built and matches perfectly to the stock X-MAXX driveshafts and bearings.