I am unburying the following from another thread: I waited to use my piercing for actual chastity security until I could stretch up to 5mm (4ga). I feel I could have done it in 4mm (6ga) but at the time MaleChastityNow didn’t offer the Prince Albert pin to secure me in the Contender any smaller than 5mm (4ga) in 2014. I have an old post somewhere here and ChastityForum/LockedMen/etc which had gathered up all the various advice and inputs from writing I had access to in 2014, including advice from Thumper (MN) and such. I think 5mm (4ga) is considered the sweet spot. Jewelry looks handsome in that size too. Use Absolutely no less than 3mm (8ga) or you risk the cheese cutter wire effect and cause migration. But I remember feeling “comfortable” but cautious in 4mm (6ga). Perhaps someone could research medical and anatomical sources to define the literal pressure (force over area) ones skin can take and not start adapting “push” out what might be considered a splinter or thorn (I’m just guessing). The wider the area, the more surface that force is applied to. And thus, the skin between the piercing and urethral opening is sufficient to remain stable. 5mm (4ga) is also light enough when wearing stainless steel rings not to cause so much force of gravity. When you step up into 6mm (2ga) and up, I found that some steel jewelry can feel heavy if not supported by clothes or chastity. It’s Not dangerous though. For heavy gauges 8 to 10 mm (0 and 00 ga) and up you really need to provide support even for plain old PA jewelry, and wear titanium instead of steel. The weight can get problematic otherwise. I used BodyCircle’s 68 gram weighted ball as a maximum safe weight to stretch, and a reference for chastity device weights. All that said, I experimented all the way up to 10 mm which really feels filling and huge. Then I stepped back to 6mm (2ga or 1/4”) and am happy there. I don’t want to go back smaller just because the jewelry I have bought in those sizes are quite more expensive than 4ga. I like wearing 2ga when my wife unlocks me to “be good” without the gift of extra help. It jangles and teases me, tempting me from my no touching rule. Finally, I know that in my 6mm PA pin with a blunt end fastened inside my Contender and Glans Armor cages, that urine seems to flow around the shaft and recombine at the tip in a way that provides a smooth laminar flow. I don’t splash or spray at off angles. As such, I can use a urinal cleanly without potential embarrassment. I don’t remember how well 5mm / 4ga worked. If someone out there has a 5mm/4ga Glans Armor, or other open front devices with a PA hook at 5mm I would like to hear how urination works for them and the comfort level of using that size to secure them in a shaft only device.