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.