Didn't know about these until recently, they're a neat add-on for electric drills to turn them into pop riveters. Reason for getting it is that about 90% of the hand riveters you can get here have a type of plastic grip guard at a position where it pokes into the palm of your hand unless you've got child-sized hands, and pretty much every one under $60-70 is cheap junk. I managed to find one of the few without the palm-injuring plastic spike on it, but it won't eject the mandrel reliably. So the response was this:

 

 

 

 

Cheaper than a hand riveter, and far better as well.