It's very low profile, a small (1 inch x 1 inch) flat black magnetic thing. It comes with a kit to hide the wire, but I just stuck it on the lid of my trunk and shoved the wire inside. You'd never know it was there unless you were looking right at it and I pointed it out. (Although my car is black.) I'd post a pic but I don't have a digicam.
Go check it out when you go to buy the other one. They have a lot of different options now. Link below to details of this unit.
Starmate Replay