The Vamo's great; it does its job, it's cheap, and it looks nice enough (it's a tube mod, you can't really go wrong). The only problem I've had with it is the centre pin gets pushed down very easily, and it can be hard to get it into the right position to make a connection and fire again, if that happens. If you are going to buy a Vamo you might have to buy a little O-ring pin stopper replacement to stop this from happening. But, again, they are cheap, and the Vamos do look nice. Be aware that the V4 does not give out the true voltage you set the device to, but rather an average of that voltage by frequently pulsing 6 volts at variable intervals.