Dremel Quick Change Collet Nut Kit 4485 Dremel AccessoriesProvides the optimal grip for bits offered for our rotary tool line The collet features small identification rings around its shank 3. 2mm Shank Diameter These rings correspond with the size of the collet: 0 rings = 1 8 in, 3 rings = 3 32 in, 2 rings = 1 16 in, 1 ring = 1 32 in For use with all rotary tools except discontinued models 1, 2, and series 1 or earlier of discontinued models 260, 270 and 280 Individual collets are compatible with flex shaft