Any recommendations for a 1/2" collet extension? I like the Infinity Extreme but for the price I was hoping for a "Made in USA" makers mark. Lots of 2 wrench extensions in the $13-$25 range. The Infinity is around $70. It uses a single Allen wrench and some kind of locking set screw. Would that put a ding in the shafts? Probably a wider soft metal end on set screw, no? Any experience would be greatly appreciated.