The doctor usually gives an injection in penis which causes one to get an erection, then an aid attempts to sell a certain method or medication that you can inject yourself for seccessful erection. It is for those who cannot obtain an erection, including those who have had prostetectomy.
Basically they sell you some stuff that you inject into your penis to maintain an erection for about 1 to 1 1/2 hours. It is very expensive, with the consultation and the medicine most likely costing about $700 altogether.
I use the injection treatment from Boston Group and it works great. I have diabetes and nothing else seems to work for me. I swear i feel like i'm 19 again when i use it! Don't let the "injection" scare you, you dont feel a thing. I was fearful until i got the hang of it, but after that there was no stopping me......they essentially saved my marriage.