It's a high quality dedicated GPS motorcycle navigator. The cream of the Garmin crop, the Zumo 550 is as good as it gets for GPS motorbike navigation. Unfortunatelty not cheap, but certainly you can get a Zumo 550 much cheaper here than anywhere else, either new or second hand.
And here is where you get the best prices on motorcycle GPS units, including Garmin GPS motorcycle units. Buy new or used, either way you'll find a Zumo 550 here at a better price than anywhere else.
And don't forget to visit our Motorcycle GPS blog.