I have been through a lot of devices over the years and have never found one that can really be worn for extended times. The CB series is awful as they have a big profile and the cage is too big for me. Even the 6000 s. I got some cheap Chinese cages from amazon as well as the Bon 4 Micro. Bon 4 quality is horrendous, and I can’t imagine anyone wearing one for any length of time. Too heavy and the metal finish is a joke with many sharp edges inside. Plus it weighs a ton. My woman thinks it might be a good punishment to have to wear it for a day. Skip that one. I ordered the Nub with the 45mm ring a few weeks ago. I determined that the 45 was too small and ordered a 50mm ring, at the same time I decided to get a Nano tube for comparison. The 50 fit better but was still too tight. I am not big balled but they hang low and too much was getting caught between the tube and the ring. I decided to go ahead and order a 55mm ring to be on the safe side. I got it in today and am doing a test wear. To be honest I can’t see much difference in size but ball pressure is less and that was the reason stopping long term wear. Thoughts on Holy Trainer The Nub Tube. It is very very small as advertised and it fits fine, but it puts a lot of pressure on the pee hole area. I looked like my pee whole had huge lips after a day pressed inside it. My woman thinks it will be a good item to wear on special occasions. Getting an erection is amazing as all of it is inside your body. The Nano Tube. For my side this fits like a glove with a little room to spare. To pee, I must carry a little sound to line up the pee hole and then press the tube backward to get everything lined up and tight. If you are not careful the pee will get in the tube and cleaning that out is almost impossible given how it fits. The process to pee, first align the pee hole with the tube slot, then push the cage backward until you are almost sticking out, then hold that pressure and aim it all down, I find two hands works best, have a wipe handy. This is all sitting. The rings seem to be random sizes. The 45mm did measure 45mm using calipers from the inside bottom to the inside top. The other 2 are not even close so I have no idea what area they measure. Quality control is pretty sad. The seam inside the tubes where the 2 halves meet is very rough. The way the tubes fit your skin is pressed very close to the plastic and any imperfections are going to get agonizing over time. I sanded it with 600 grit and lapping compound and a scotch bright pad. That made it better and time will tell if long term is possible. For this kind of money there is no excuse for poor quality control. As a comparison I ordered a cheap knock off and to be honest, I can’t see any difference between the real deal and the fake quality wise Bottom line is I can’t recommend Holy Trainer because of price vs quality. Lower the price or pick up the quality.