Shimpo Ball Mill Rack for Potters WheelAttaches to all wheels when used with a 12" wheel head (except the M1). This space saving rack will allow you variable speed milling and grinding. The rack accommodates jars from 3 1 2" to 9" diameter up to 10" long. Made of heavy duty cast iron, the unique folding design lets you use your SHIMPO wheel for throwing without detaching the rack.