Do a search on Cialis, Viagra, Levitra, etc. if that's what you're asking about. Lots of input from members on these.
One thing I would say about erex (or any other similar product) is that although I've tried it and had excellent results, I'm reluctant to continue using it. I had discussed the usage of it with a nurse who brought up some important points. What exactly is in it? Any clinical studies? I mean how do you know it won't react adversely with other meds? I think I'd rather pay extra for some peace of mind.