I have tried one and it will get your dick hard and red. You slip the cock ring on and you stay hard and red, at least I did.
As good as it sounds don't over pump as I am sure it can cause some serious damage.
I would recommend just using a cock ring. Slip it on when you are soft, watch some porn or play with yourself, and the ring will trap blood and give you a very hard erection.
I have left the ring on and stroked to a climax with no problem. When my cum starts flowing I get a mighty first shot then my cum starts dribbling out until I start to soften.
I wear a ring often and use lube and have a grand ole time.
