
It produces 'mushroomed' ends on tee nuts to avoid them backing out of the hole:

Only problem is that you have to buy the tee nuts from Rockler as they must be the ones designed for this task. However for a couple of subs paying £9 for the bit and £6 for 20 tee nuts isn't too bad. Sorry for the £ sterling, I've only got the UK pricing on Rockler's site, but it's probably about the same amount of $.
They might be a bit tight (on the Lab's at least) as they are 1/4-20. The eminence data sheet quotes 0.26" as the bolt hole diameter.
Video here: