i was sceptical like you on if this was actually going to work, well men it does, first time i used it i cam in only 5 minutes of using it (while watching porn) does what it says! could be a tighter yes but if you want that then use your hand. Im 4 1/2" girth so picked size B. wondering if the smaller size would be better? but if your looking for something to get you off with out moving a muscle look no further! Ps its a bit noisy basically need head phones to watch porn while using it. hope this helps!