I’ve been bruised with steel. Go with Silicone rings.

I'm curious about this too. I've a ring built into my prostate massager. Love that it hugs my balls together and pulls them out a little, think it makes my erection stand a little taller also.

OH WOW I had no idea that it could happen

Fascinating! Have you already posted a pic using it ? Did you craft this yourself or did you buy it with the ring included?

It was built in already. I’ve posted a few pictures using it, works wonders for me & I love how much more sensitive my balls are with it on.

I have used a few different types. I just love all of them. One tip I would be clean shaven as putting on and taking off with hair can hurt a bit.

I have used cockrings a lot and yes they do assist in maintaining an erection for me. I find they fit and work best using a bigger ring that fits over your cock and around under your balls like a chastity cage ring. I also like to put one just around my scrotum to present my balls like in a package to my partner. They are not that expensive so get a few different sizes and thickness to experiment with to find a tightness that works for you and is comfortable enough to wear. They do get sore after a while if they fit around or under your balls very tight but if you are like me and your balls pull up when you get quite excited, you need to find a tight enough fit to keep them in place. The soreness develops after some time, because of stressing micro-muscles in your scrotal skin that normally contract and expand your scrotum to control the temperature of your testicles for healthy sperm production. It seems to be that restricting the blood flow on the upper side of your penis near the base is what helps men to have and keep an erection so I favour one that encompasses your balls too. Yes, as '840, said, shave your whole area or you will be pulling hair like crazy. Also for removal, thicker rings are easier to grab than thinner ones without pinching skin. Generally thicker ones are stronger but there is a difference in their strength between the more rubber like and the softer somewhat jelly type of silicone. DO NOT keep any of them on for any longer than for a moderate period of sexual activity because they all restrict blood flow.
As for metal rings, I have used them carefully and never experience any bruising. I say carefully because you have to ease squeezing your cock and balls through them rather than just stretch an elastic one over them. Don't let an elastic one snap or it can be like a kick in the balls. Metal ones are more expensive and depending on fit, they don't feel any more or less comfortable but for some fits they do not keep squeezing like the elastic type.
I have also tried the strap type and although they are a bit of a compromise between metal and silicone, I found the roughness very uncomfortable.
Good luck!

I love using cock rings and glans rings. Check out some of my photos and vids. I have multiple rings around my cock, balls, shaft and cock head. Makes for a nice intense orgasm!!

I also found this one: https://www.balldo.com which is a bit different but interesting

I did look up BallDo.com and they did have an excellent selection of cock rings, ball extenders as well as cock and ball separators. I really liked the gender X racketeer and cannot wait till it gets delivered to my home. They also have lots of other toys.
My favorite though is my silk on Baldwin cock separator made by tri-sport. I love to wear it underneath my see-through shorts on the way to the nude beach that I go to. Makes my cock and balls the so delicious and get many good comments and looks on my way, just love it. It also keeps the blood in my penis so it stays semihard as long as I have it on. After I put down my chair and blanket and dropped my shorts I will usually walk around the beach sporting my cock ring for everybody to check me out. Here is a picture of my favorite.

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Cock rings are awesome. Flat out. The trick is to get the right size. You can measure yourself with the string technique or a tape measure. Once you get your right size then you can be more selective about what types. A properly sized cock ring can be worn for long term. I have some that I wear all day. I have some that I just wear while having fun. If you’re new to them try to start with a leather speed strap. It’s a cock ring made of leather with snaps on it. You can size it as you like, and it’s easy to take off. There are silicone rings, but for a keen trick go to your local hardware store and buy a number of various sized silicone o-rings. You can experiment cheaply and they’ll give you a sense of how to use them. The hardware store also has cheap steel rings, usually in the rope and tackle section. You can use those too if you want to cheaply try steel. The trick to solid cock rings is putting them on properly. You do it flaccid before the fun starts. One ball at a time, then pull your flaccid cock through. Taking them off is the reverse process, but you must be flaccid. If you are hard, it won’t work and you’ll hurt yourself. Speed straps are good because you can put them on hard or soft. Once you have gotten comfortable with the cock ring they are AMAZING. You’ll love how hard you get. It’s so awesome to hold such a hard cock.
I have a huge collection of rings. Couple of speed straps that I still use. I have a few silicone ones. I have many solid rings of a wide variety of materials. Steel, Silver, Copper, crystal, Rose Quartz, jade, wood, Tungsten Carbide (love the weight, but expensive). You can find exotic materials if you look for bangles. You can get glans and shaft rings custom made from some jewelry sellers once you know the right inner diameters. I really enjoy cock rings.

I love cock rings! Have several and usually wear multiples at the same time. Love how the weight feels. I have 1 that has the attached butt plug that's so fun to wear. Also, a figure 8 shaped 1 that is amazing. I think I may have a picture of that. My cock and balls go thru the bigger loop and I bend my penis head up thru the smaller loop. Feels so good. Sometimes I just put my balls thru the big loop and bend my penis down thru the smaller. Either way it's awesome.