I have long suspected that simplest is best and this is a product that proves it. I have bought 2 similar products: one had a much thinner cord which became quite uncomfortable after a fairly short time and cost about twice as much; the other had a thicker cord which was effective but nowhere near so effective as this and cost about three times as much.
The beauty of this gadget is that it has two balls to maintain the degree of tightness. This means you can get it tighter than any other similar ring will allow but it still permits quick release. All you do is tighten the ring with the first ball, lock that in place with the second, and then you will find that you can tighten the ring still further by repeating the process.
I would suggest buying at least three: one to go round the cock and balls as normal, then one for each ball. the effect is truly impressive both to look at and to feel. Your cock feels like the King of the Universe if you're wearing the of these rings. Actually, you'd be better off buying six of them: that way your partner won't feel nneglected or leave you frustrated by borrowing yours.
Highly recommended!