This small, light ball caster uses a 3/8″ diameter plastic ball. The height of the assembled kit ranges from 0.4″ to 0.6″, depending on the combination of included spacers used.
This ball caster kit includes a black ABS housing, a 3/8″ diameter plastic ball, two spacers (1/16″ and 1/8″ thick), and two 7/16″ #2 screws and nuts. The total height of the ball caster, 0.4″, can be increased to about 0.6″ using the included spacers. The two included #2 screws can be used to mount the ball caster to your chassis, or you can use your own #2 or M2 screws if your application requires a different length.
Note that our ball casters are designed for small robots; they are not intended to bear more than a few pounds. With more weight than this, friction between the ball and the housing will generally keep it from rolling well.
For detailed dimensions, see the dimension diagram (164k pdf).
More technical information at Pololu.