Well, it seems I am now part of the #chastity gang. I fantasized a lot about it and I guess the blog of @thumperMN is to blame for that. I tried different models in the past like the cb-6000, but they fell of during the day and were clumsy. I ordered a cheap metal micro device... ...and couldn't even put it on. But yesterday out of the blue I tried a silicon device I bought long ago and which didn't seem to work - and had it on for 24h. It worked fine, even on my uncut cock.