You receive in the box two items. The first is a thin, credit card sized transmitter. The second is a palm-sized receiver on a key ring. You simply turn on the transmitter (which will then display a small red light on the edge) and press the marked button. The receiving unit will then light and beep. I'm not just talking about a minor bleep", I'm talking about a loud-enough-to-be-effective beep you will most certainly hear. Pressing the button on the receiver will turn it off.
The transmitter is the perfect size to fit in a wallet, so it's never obtrusive or in the way. The receiver is also small enough not to be burdensome when it's attached to your keys. Five big gold stars from me for a product that worked out of the box and did the job it professed to!
Note: I received a discount on this set in exchange for an honest review.