A series of chastity devices purchased over the last three months litters the trail of our journey into chastity. I gather that this is not uncommon. One has gone off to a new home, one is now rusting in a landfill somewhere, one broke, three sit in a dresser drawer, only two of them really wearable. I like the Holy Trainer, but cleaning can be difficult, you have to be careful not to put pressure on the part of the tube that the lock goes through when it's warm, like after a hot shower, or it might break. I did a review of the Bon4m large some time ago but I couldn't wear it. Hitting the chair on one end, pushing into my abdomen on the other, twisting into odd positions in my jeans the longest that I could wear it was a day, maybe two at the most, even though I smoothed the inside. Even modifying the shape of the larger ring didn't help. I gave up on it.
I think that I may finally have a cage that really works, though not in it's original configuration. I've had it on for over a week now, and had a 4 day stretch without taking it off at all. No pain, no sores, no skin damage. Much more comfortable than any other metal device I've tried. The HT is still the most comfortable and "transparent" if you will, meaning that you aren't aware of it most of the time. But needing to take it off every morning to clean is an issue for me.
I've always been drawn to a cage like the Bon4m. Heavy though it may be, it looks cool, it's solid and I like something that I can wear and clean well without taking it off. The short story is that I was able to get just the short cage without the rings (which I obviously have already) from a distributor. I thought that the shorter length might be the key, and it is. Even though I measure around 3" flaccid, the 2 1/2" inside length is perfect. When engorged, it limits how erect I can get, and I don't swell out of the holes like I did with the large version. When flaccid I don't always reach to the tip, but close most of the time. It fits well in pants, doesn't shift around, and isn't at all conspicuous.
But I still say that it needs some help before you want to wear it. The inside of the cage isn't smoothed and polished like the outside. The manufacturer provides sand paper, and you should use it. I used a rubber polishing wheel on the inside in a Dremel like tool to polish and smooth. Not mirror smooth, but better. I also ended up taking 400 then 1500 grit wet/dry sand paper to polish the inside of the bars. Cut them into thin strips and loop through the holes and sand the ridges off of the bars. All of them. It made quite a difference.
The other issue is the rings. Sizes are good, but the rings are square, not round. I always had a problem with a "pinch" on my sac, even with the new cage, and it wasn't from the hinge. I rounded the inside of the ring a bit and smoothed it, but that didn't help. I finally figured out that it was the outside of the ring that was the problem. The square edges of the ring were digging into the skin, preventing it from sliding over the skin even with some oil on things. So I beveled the outside edge of the ring, and then rounded and polished with the rubber abrasive wheels, then buffed. What a difference. No pinch.
You can see the rings as they arrive in the review here - http://chastityforums.com/viewtopic.php?f=3&t=59839
But I still wasn't satisfied. I had a small device that had a solid 45mm ring that worked well. Even if the cage had issues, the ring always felt comfortable. I ended up with an extra identical ring, so I decided to modify it to fit the Bon4m. I turned the locking pin down to fit in to the Bon4, and drilled holes in the ring to take the Bon4 guide pins. I had to bend the ring itself a couple of times to get the gap right, but it works. Comfortable, and I think good for long term wear. To tell the truth, I'm excited to have a metal device that I can just leave on, and not take off unless my wife wants it off. And it looks cool. I find myself looking at it in the mirror when I'm in the bathroom...

Here's the completed device with the modified ring. Too bad Bon4 doesn't just make them this way.