IFMAR legal, specially-designed 4WD front wheels with 12mm internal hex. Perfect fit, and ideal for high-competition race. The wheels are manufactured from versatile material while nevertheless being durable against effects. The side associated with wheel is aerodynamic for optimum performance. Medium hardness. Unique features of the wheel are noticeable from inside: reinforcement ribs to really make the tires as stable as you can and eradicate deformation. Set of 5 pairs (10 pcs) the cost of 4 pairs. An excellent value pack. Fits all XB4