Hi, To answer your questions pirate, when I bought my two shaft collars I got the black oxide ones instead of stainless steel and they did rust when I grinded the edges. I just ended up puting medical tape over the rust and I always wore them with a sock or cloth and maybe a cable clamp for a spacer.
I would not recommend skin on steel contact at all unless it's a special kind of steel like the ball
weights sold on secret leather. When I was wearing the regular shaft collars from mcmaster carr they were fairly comfortable with the sock but I stopped wearing them because they weren't convenient to me always having to put on a clean sock and cloth so I didn't really like having all that stuff on my balls all day.
If your serious about ball stretching you need that extra comfort. I want to get the WMC ball
weights found on secret leather. They are made of a special kind of steel and have no edges so you can wear them on your skin with some cocoa butter and have them on 24/7. I would get two 15mm
weights with the spacer bar it looks really well made but it's not cheap. I really want them though maybe DLD can get a discount b/c I think they have potential.
I imagine you can wear them through out the day and while sleeping and feel pretty good like your balls are always being stretched with comfort. They can help keep the balls low while in the [words=https://shop.mattersofsize.com/products/sizegenetics-penis-extender]
SG[/words] and the [words=https://officialhydromaxpump.com/?uid=6&oid=2&affid=98 ]
Bathmate[/words] so it sounds sweet I've been wanting them for a while now actually.