The Hegar Urethral Sounds are Chrome Plated Brass and has a total of 8 in the set. Each sound has two sizes one on each end so it like getting 16 for the price of 8. They start at .126 inches up to .739 inches. These set is used to increase the size of your urethra. This kit allows you to do this gradually and gently. Many have also used these anally, vaginally or on the prostate and have some great things to say. This is a very nice set and would make a great gift.
You should never force anything, as soon as you start to feel pain or resistance; it's time to move to a smaller sound. It is very important when using sounds please use common sense and make sure you have researched urethral play fully before you start.