Rubber Sealed Collet

I'd be pissed, too...using an undersized collet is a definite = no-no....suggest contact the seller or buy a 1/4in collet asap

Here's a good read on the topic:

--of all of the machinists I've been aquainted with over my lifetime ( = and there have literally been thousands ) he would easily rate into the = top ten so far as expertise in the field is concerned.=20

Yep.

I have a 1/4" in my other set, but a couple times I have had need of two of them at the same time in order to make a job go faster. I was ignored by the seller, but the set was inexpensive enough. I think they were retiring, and just made a mistake when they packed up the set and shipped it to me. The 1/4" one probably went out to whoever bought their metric collets. LOL.