Take a lubricant of your choice and apply some lubricant to the inside of the cock ring.
Then gently slide the ring around your flaccid penis . It is important that you use the correct size with a metal cock ring, as a metal ring does not stretch with the body. If the cock ring hurts when worn, the ring is too small. Then remove it as soon as possible to prevent damage.
To determine the right size, make sure your penis becomes erect. Then measure the circumference of your penis with a measuring tape where you want to use the cock ring. Divide the circumference by pi (3.14) and you have the inner size of a suitable cock ring .
Do not wear a cock ring too often and never longer than 20 to 30 minutes for safe use.