Out of sheer curiosity, I bought one about fifteen years ago. I had a British girlfriend at the time and she would wear my ass out on a regular basis. So, I tried the pump.
They certainly work. No doubt about it. The problem I had was that once you pump it to full capacity...you can't get out of it. You have to wait for the erection to subside a bit. I would recommend using a generous amount of lube around the base to make sure he doesn't have the same issue. And, no, getting stuck has nothing to do with size...the damn Brit wouldn't stop pumping.
Wow! I may have shared more than I really wanted to there...
I've been using a Vitality pump for years. Works great, but the constriction rings are tough to use. There are better ones available. The Vitality pump used to be prescription only and $400.00. Now they are over the counter and $100.00.