I'm not going to waste time with a fluffy intro. Let's get to the business of why you might want to buy a cock ring for your guy.
He'll last longer. First and foremost, cock rings prolong erection time because they restrict the blood flow. This is ideal for anyone who experiences premature ejaculation or if you just want to keep the party going a little longer than usual. There are other male masturbators that can make him last longer but this is another story.
He'll get (a little) harder and bigger. They make the cock harder, leaner and meaner. They allow for a raging hardness and plumpness that you'll both enjoy. This means a slight temporary increase in size. Fun! Be careful though, too much of a size increase means that the cock ring is too tight and could become too difficult to pull off. Take that ish off immediately!
He'll have better orgasms. Much to his pleasure, cock rings also contribute to more intense and often longer orgasms. Some claim their orgasms last up to a minute! The holding back allows his orgasm to be more pleasurable and can lead to increased splooge volume! Who doesn't want to have the best orgasm possible?
Choosing the right cock ring:
I always advise against using metal cock rings. It's just too hard (heh) to gage what size you need. Obviously metal doesn't stretch, and if you realize that it is too small by the time he is too hard, this could mean a trip to the hospital. Some expert cock ring users can get away with it, well congrats to them. If you're not an expert, just keep the metal away from your cock.
Go with something flexible or that has some give at the very least. Rubber is super stretchy. 100% silicone is less stretchy, but has a nice give and is body friendly for both of you (won't cause any skin irritation). Leather is another option for those who like to dress their cocks up a bit in fine Italian clothing. This type usually comes with snaps, so even if the leather doesn't stretch it can be easily removed.
You want the cock ring to fit snug when flaccid, but not squeezing the life out of it. If it starts to hurt or feel cold at any time, take it off! Feel free to use some lube to help get it on and take it off. You might get pretty excited the first time you experience the magical powers that belong to the cock ring.
Do not leave the cock ring on for longer than 30 minutes.
I know, you'll both be excited about boner time, but remove it for his safety.
Want a little buzz that you'll both enjoy? Try a vibrating cock ring!
Happy cock ring shopping!