The Camco multi-clamp has been discussed here before. Here are some posts:
"Power Uli Device"
Camco Multi-clamp at Walmart
I’ve been using mine for the past few days for some intense girth work. My super hot friend — who is easily the sexiest, most beautiful woman in the world — told me she slept with some guy in Ireland once who had a dick as thick as her upper forearm, which appears to be about 7”. She says I’m already hung, but now I’ve upped my girth goal to 7. But, if I gain a 1/2 to 6.5 I’ll be happy. She says the guy was huge, but also a poor, drunken freak. (I’m usually only one or two of those things at a time.)
I use terry cloth wrist bands for wrap. I put the multi clamp tight around the base, and then when I’m really engorged I put a cable clamp up just under the glans. I do three or four sets of that with 10 minute pump sessions in between. This is very intense, advanced stuff, and should be done with extreme caution.