I use this stuff when swinging or visiting a sauna, so I can keep hard all evening, no matter how many times I've cum. Recently the government has closed down sites selling cheap - on often fake - anti-impotence drugs; I've had Viagra and Kamagra from such places in the past, and had at least one bad batch. They've closed such sites down as most of the stuff sold these days is bogus.
It's only available in UK on prescription, and doctors aren't going to be very sympathetic if you go to them and ask for Vigara for group-sex. You can get around this by getting Vigra/Levitra/Cialis from an on-line doctor; you fill in a medical questionnaire which a genuine doc will look at, and either send you a prescription which you can get made up at any local pharmacy, or send on the drugs by post. I've just had a batch from Lloyds Pharmacy, such an on-line company, although there are several more reputable ones.
I tried out the Viagra in my local sauna club last week, it certainly was the real stuff!