This Collet Nut Kit helps to improve the grip for a wide range of bits in the Dremel multi-tool line. The collet itself features small identification rings around its shank and the rings correspond with the size of the collet. The individual collets are compatible with flexible shaft attachment. The kit included 1 collet nut and 4 collets (0.8 / 1.6 / 2.4 / 3.2 mm).