Pololu ball caster kits with spacers and screw sets pololu 953 this ball caster kit has a 12in diameter metal ball the kit includes a black abs housing a 12in diameter metal ball two 18in spacers and two 2 screw sets the total height of the ball caster 053in can be increased by using the included spacers to approx 07in this ball caster is just one of the many pololu accessories carried by rapid for further resources please see here pololu 953 ball caster 12 inch includes t