The most popular Metal Cock Rings are chrome. They are more expensive than rubber or silicone but some men like the heavy feel and the smooth touch. There are various sizes and weights.
Metal Cock Rings are cool when you put them on but then they warm up to the temperature of your body heat. If you are the kind of man who want to feel more metal around your dick, try the Teardrop Chrome Cock-Ring. This works like a push-up bra. It is made to lift you up and keep you hard. Both your cock and balls will go through the hole with the metal tapered point pushing against your perineum. This metal cock ring is made from brass and then chrome plated.
Metal cock rings are not for everybody because they weigh more and might not be as comfortable as a soft material. It is a personal thing.
