This is 68mm rubber wheel for DIY robotics car project. The wheel rim is made of the reinforced nylon material. The rubber of the wheel is high quality. It is wear-resistance and deep groove for high grip anti-skid. You can find the matching motor shaft coupler for Ø5 ~ Ø8mm shaft motors. With these wheels you will be able to get almost any beginners robot project moving. 1-piece/pack. General Specification: - Rubber Material: Soft Rubber. - Rim Color: Blue. - Wheel Outer Diameter: Ø68mm. - Wheel Width: 26.5mm. - Deep grooves for high grip anti skid. - Matching motor hex shaft coupler for 5~8mm. - Motor Mounting with Hexagon Shaft Coupler. - Weight: ~38g. - Color may differ from photo depend on the lighting and angle of viewing. Image is for package illustration purpose only. Refer to product specs for detail.