Self explainatory name! I've seen several holders, but they usually use the vents of the car, and i don't like to block them. This one fits in the gap most cars have for wallet, keys or phones. It uses an M6 screw to adjust the distance of the gap so it can fit different spaces.
Additionally, it could be used in any gap you like, or even be used as a clamp, due to the adjustable holder.
It fits iPhones 4 through 5S (same width), as length is not constrained. I've given it a little space for a case, as most of us use them. I've added the case model i've used, in case someone wants it!