12mm Aluminum Wheel Drive Hex Hubs 20mm Longer Combiner Climbing Simulation Coupler For AXIAL SCX10 AX10 4WD D90 F350 RC Car Upgrade Parts (Pack of 4) HEX 12mm Length: 20mm Diameter of the Hole:5mm Pins:2*10mm Compatibile with: AXIAL SCX10 AX10 4WD D90 F350 and so on