TechnoTed: I have used the Erecaid cockrings for years for pumping and sex. Never a problem. The cockring makes my hard cock super-hard, expanding it to its full 2". That's not huge but its very effective. ;D I use their tightest ring, but only for about a half hour at a time. You will know its time to remove it when it start tingling, feels numb and somewhat uncomfortable. If you are using those stretchy cockrings from porn stores, you could wear them all day because they are way too soft (stretchy). You can check out the Erecaid cockrings (they prefer to call them 'tension rings'...) at
http://www.timmmedical.com/erecaid/
or ask them about the rings at 1-866-240-8071. You can buy one or get a discount if you buy two or more. Get together with a friend that wants these super rings too (maybe some here on this forum?) and take advantage of the quantity discount.
I have also seen them on ebay. Type <erecaid> in the ebay search engine. At this time there are 3 Erecaid systems offered so you can see the rings in the picture. I have used the Erecaid system for years for successful enlargement of my cock, in case you're interested.
Good Times.
TechnoTed