How they work...
To understand a cock-ring you need to understand the erection: An erection happens when arousal causes the brain to send signals to the specialized blood vessels in the penis. Blood flow to the penis is vastly increased and this specialized penile tissue is engorged. Increased blood flow during sexual arousal and throughout activity keeps this tissue engorged, which has the effect of maximizing the size the tissue can expand to, and hardening the penis in the process.
So back to the cock-ring...
Essentially the purpose of a cock-ring is to create a situation where the blood can't escape the penile tissue as easily as it can enter it, resulting in some mens' penises becoming slightly more engorged than normally possible (so, a larger erection, in some). The body is naturally very good at pumping blood in, but it doesn't really actively pump blood out. The evacuation of blood is mostly due to the circulatory process of moving the blood in...it pushes it along. So this concept of engorging by pinching off works pretty well for most men.
With those mechanics in mind, we then have an explanation for the staying power feature of cock-rings. If it's harder for the blood to escape, then when the flow into the penis begins to decrease slightly, the blood is being held in the penis a little more aggressively. So where a man normally hits the point of going flaccid with their decreasing blood flow, they might be staying a little harder.
All of this mileage is going to vary from man to man, penis to penis.
Will they increase pleasure? There is a change in sensation, in my opinion. With all of that blood flow, most men experience an increase in sensitivity throughout the penis. But whether that's pleasurable or not is subjective. Personally, wearing a cock-ring increases the sensitivity quite a bit, but the feeling of the ring can actually be distracting and impact my arousal levels.
As with any sex toy or device, cock-rings are safe if used properly. But no matter if you're using an appropriately sized ring in a safe and proper manner, you must not wear a cock-ring any longer than 30 minutes. After a few hours of having an erection for any reason (constriction, pharmaceutical drugs or herbal products, or even just being that aroused for that long) can cause permanent and irreversible nerve and vascular damage to the penis. And I mention appropriate size because even short periods of too much constriction can cause similar damage.
And a note on penis pumps: These are used in conjunction with cock-rings. You slip the ring on, and then use the vacuum pump to force the blood flow into the penis which is retained with the aid of the ring. Use those properly, too. Over-engorging the penis manually in such a fashion can cause a lot of damage!
Types of rings
There are two basic kinds of cock-rings, and some of the sophisticated ones are various combinations and variations on these: One is designed to go around the base of the penis, resting on the underside between the shaft and the scrotum. The other design has the ring resting on the underside behind the scrotum, between your scrotum and perineum (the area between your scrotum and anus). Both setups have their pros and cons. Past these two basic types, you have cages and multi-ring harness setups...there are a lot of different kinds.
Cock-rings come in a lot of materials. I loosely group these into two types: elastic and hard. Your rubber, latex and silicone rings that have noticeable elasticity are the elastic types. They are very common and the safest to use if you have the right size. Rings that are made of metal, hard plastic, or hard non-elastic rubbers are the hard ones. These can be dangerous since you might run into a situation where the penis swells around the ring; if this happens you might not get it off, which will constrict and can cause additional swelling. People who don't know how to use these rings properly often have to make a very embarrassing visit to the ER to have them cut off. And by then, many people have suffered irreparable damage to their penile tissue.
Make sure you know how to use a hard cock-ring before you try it out. Do your homework. Go to a reputable adult toy retailer, find a clerk that is knowledgeable and passionate about their product, and. engage them.
Buy one from a legitimate and reputable shop that sells sexual devices. Often there are salespeople who know their products and can help to find the right one for you. Start with silicone cock rings. Get one that is super stretchy. It should fit snugly, but not too tight. Write to us at firstname.lastname@example.org and we will be more than happy to explain to you how to use it and which to buy as the first one.