IFMAR appropriate size, specially-designed 2WD/4WD straight back tires with 12mm interior hex. The guts countersunk area was redesigned to put the wheel nut further. Precision fit, ideal for high-competition battle. Made from versatile, durable product to withstand results. The interior the wheel is aerodynamic for maximum performance. Moderate hardness. Unique shows regarding the wheel are noticeable from inside: reinforcement ribs to help make the tires as stable that you can and expel deformation. Group of 5 pairs (10 pcs) the price of 4 pairs. Outstanding value pack. Fits all XB2 & XB4