IFMAR appropriate size, specially-designed 2WD/4WD right back tires with 12mm inside hex. The middle countersunk area ended up being redesigned to position the wheel nut deeper. Precision fit, well suited for high-competition race. Created from versatile, durable product to withstand impacts. The medial part linked to wheel is aerodynamic for optimum performance. Medium hardness. Unique highlights of the wheel are noticeable from inside: reinforcement ribs to help make the tires as stable as you possibly can and eliminate deformation. Wide range of 5 pairs (10 pcs) the price tag on 4 pairs. An incredible value pack. Fits all XB2 & XB4