I have been using the Osbon Erectaid - manual for about
9 years.
The unit is expensive for what you get but it does last a long time.
I have update two years ago to the newer manual version.
It works, it something which you need to practice as well as take your time.
When I first got it, it was pump, pump, pump and not wait until Jr. naturally expands. The result was uncomfortable and when I put on the rings, it kind of hurt.
I have learned that with practice and patience, Jr is more comfortable with the process and he doesn't lose his fealing because of too tight and wrong bands.
I have used various rings and found the D rings as well as the Round inserts work well. Sometimes I use two rings, a D ring and a larger ring but the more time I take pumping up the less I need two.
Unfortunately using the pump does put a pause in the love making process but the results are good. Both my wife and I enjoy how it works so YEAH!
Good Luck and Good Pumping.
Tom of Ohio