These plastic wheels have silicone tires and measure 40 mm (1.57″) in diameter. They mount onto micro servo splines with 20 teeth and a 4.8 mm diameter.
This product is a pair of wheels.
These wheels are great for robotics, custom RC vehicles, or any other project you need to get rolling. They measure 40 mm (1.57″) in diameter and are designed for use with micro servos with 4.8 mm diameter splines with 20 teeth, such as FEETECH’s FS90R micro continuous rotation servos and FT90R digital micro continuous rotation servos.
The combination can serve as a small, inexpensive, and easy-to-control drive system for a miniature robot. The wheel presses onto the servo spline just like a typical servo horn, and the small screw included with the servo accessory pack for mounting servo horns should be used to hold the wheel in place