A very small or at least, very short cage, the Nub HT V3. I received mine several days ago and I immediately put it on. I still marvel that I can easily fit my cock into something so small. Looking down at my package now, I can only see the base ring and am forced to lift my balls and everything up to see the little nub part where the head of my penis is trapped. The small pee hole and the tight fit means I'm forced to sit down to pee which my wife really likes. I'm sitting here unable to get hard because it's so small and the top of the penis cover extension forces everything to face downward. It's comfortable on me and gives me the deep frustration for which I crave. I hadn't had a cage for at least 6 months so putting it on brought back all the feelings of horniness and tension that I missed. The feeling were so amplified that I was very nervous to give up the keys but I found myself going to my wife to give them to her. It was very inexpensive, like $15's and I'm glad I'm locked up in it. I miss my nightly masturbation and don't have an idea when I might be released. They make it out of metal and I should get that instead but initially I just wanted to try the design out before making a bigger financial commitment. Just happy
I purchased a resin Nub but plastic does not provide the security of steel, so I purchased a stainless steel Chinese knockoff that is totally secure with a steel waist band. It is comfortable enough to wear for weeks at a time. As you say, you can only see two balls and the shinny steel cage and no way to escape the frustration the trapped penis.
I am wearing the same version shown in your picture. It is surprisingly comfortable to wear. I have not yet attempted to wear it at night. I also just bought the steel version of it and am anxiously awaiting it's arrival