5C Spin Index Features include... Indexing Plate with precise 36 hole pattern Base size: 5" x 5" 10 vernier holes for 1° indexing Hardened and ground spindle with lock. This is a multi-purpose indexing fixture designed to extend the work capabilities of surface grinders, drill presses and all types of milling machines. Accepts 5C collets to 1-1/8" capacity.