Dremel 4486 MultiPro New Style Keyless Chuck. Will hold bits with shanks that range from 1/32 inch to 1/8 inch. New Style keyless chuck (will work with the flexible shaft, but not the model 332-5). Use with rotary tool models 275, 285, 395, 398, 750, 770, and 780. Also use with Dremel attachments 212, 225, 575, and 961. Other brands and models will work if they have 7/16 inch or more threads on the shaft with the collet nut removed and they use a standard Dremel collet nut. Not in retail packaging.