I've been practicing chastity for I think almost three years. For just over the last year it has been 24/7. It's been a daily part of my life. I tried a couple devices before landing on a contender from male chastity now. Using sizing rings, I believe I got a pretty accurate measurement and had the device made. My first cage was about 1.75" or 44.5mm in length and 1.125" or 28.5 mm inner diameter. it was a great fit. I'd say it was perfect for beginning to get used to 24/7 lock up. After some time I felt like I could go smaller now that I'd gotten some time under my belt. I'd also noticed when I get extremely relaxed or hot things would think out and extra space was noticable. Next device was a modified glans armor from male chastity now. I had a masturbating failure with the shaft only device so I was not allowed to use it anymore. I took the opportunity to modify it into a contender since they are basically the same device. Only difference is the attachment for a base ring. That device was a bit shorter. 1.25" or 32mm in cage length and still 1.125" or 28.5mm inner diameter. I found this to be even more comfortable. When becoming aroused it was less uncomfortable. The erection was being stifled before it could have a chance to really pull on my testicles. I've been in this device the longest. Well I recently decided to take the plunge and make a diameter change. When cleaning I can get my thumb in the cage with my penis. That just seemed like too much room to me. But it looked ok otherwise. My penis wasn't swimming around. It's amazing how malable the penis is. I was also shy about going smaller in diameter because of edema. Happy to say I've been in my new device for about a week and it's wonderful. Only slightly shorter. 1.188 or 30mm in length. And down to 1.0625 or 28mm inner diameter. A 1/16 of an inch or .5mm doesn't seem like a lot but in terms of diameter I can definitely tell a difference. The extra constriction really keeps the erection attempts at bay. Very comfortable, I'm a believer the smaller the cage the better if you're a grower. Attached are the first two cages and I uploaded a thumbnail of my third as I'm wearing it.
I have had a similar experience. MCN made me 1-3/16” ID cage by custom request after two years of wear in 1-1/4” ID. I wanted it to be a slightly tighter grip. I also had a GlansArmor2 made into a Contender as well. I might end up getting a Contender of the same diameter someday. I just can’t decide on the proper length. I had “cage stuffed” and I’d like to try a longer cage at the custom ID