Easy to mount, durable and cheap. These wheels have a 6 mm hole for shaft with screw for fitting making it very easy to mount on motors.Big Wheels Highly Durable and Resistive.Heavy Load Bearing Capacity.Robot Wheel 10 cm x 4 cm 6mm Shaft. Package Includes : 1x pcs 10×4 cm Robotic Wheel Category: Tyres & Wheels