Primarily to let blood flow in and dramatically slow it down when leaving. Although there are different kinds. Personally I love the surgical steel rings. When sized properly, they can be worn 24x7. I stress when sized properly. You can get a 3-pack of silicone rings just about anywhere. Small, medium and large (unusually around 1 1/2”, 1 3/4” and 2”). I personally think they’re uncomfortable. Another reason why I like steel. They aid in keeping an erection longer, and slightly larger/harder by preventing the outflow of blood. Lots of information online. Hope that helps a little.
