Yeah, well it's very similar. So be careful with cock rings too.
But clamping is more extreme. You just put a cock ring on your boner to make it harder and more impressive. With clamping, the aim is expansion, so you put it on at about 80% erection level, and then adjust the clamp in small increments until you find the perfect setting of blood going in, but zero blood escaping, and balloon the size of your cock.
You can see why it's dangerous eh?