When connected to a compatible camera - either on the hotshoe or via USB, the Canon GP-E2 GPS Receiver can be used to geotag your photos and videos, record your route or even turn your camera into a digital compass.
Alternatively, the GP-E2 can be used independently as a standalone GPS logger. Just turn it on and it'll record your route internally, ready to be downloaded onto your computer.
With only one switch, it's super easy to use. Just switch it 'on' when using with a camera, or 'log' when using on its own.