For jewelers appreciating a quick change of bits particularly when using 332 and 18 mandrels one must invest in this item.Rather than using collets and the collet nut on the dremel flexshaft handpiece this universal chuck holds both and larger mandrels, small drills and other items used daily in making fine jewelry .Even metal clay enthusiasts will find this an essential item in your dremel accessories inventories. If one keeps it free of metal bits by simply brushing them out daily into marked film cannisters for eventual refining- or removing the chuck and blowing it out with canned air it lasts about a year with regular use.In studios without air conditioning it may rust if you do not apply some inhibitor- in fact that is its main drawback.The only other limitation is with overheating by running the tool at too high a speed for the bit in use the jaws may become malaligned.Once malaligned replacement is , unfortunately the only lasting remedy. Overall it is a handy addition to the flexshafts handpiece functionality in terms of time saved - It is worth every cent