The OWow looks like a brilliant product: a cockring with a nubby clit tickler on it seems like a no-brainer. My only problem with it is that it doesn't fit me!
The ring part itself is made out of a very nicely stretchy material, but the initial diameter on the thing is quite small. Fully stretched, I get closer to tearing the thing than actually getting it on my dick. And the idea of then constricting bloodflow that much just is not up there on the fun list.
So while I appreciate the idea, I wish there had been some multiple size options here. Guys with a bigger girth are going to struggle to keep this one comfortably in place.