Garmin 50LM Official Site
You can read many details and information about Garmin 50LM in their manufacturer site. Details like complete features, technical specification and etc.
http://www.garmin.com/us/

Garmin 50LM on Wikipedia
In this wikipedia, you can browse the complete list of Garmin  products including Garmin 50LM.
http://en.wikipedia.org/wiki/Garmin

Garmin 40LM
Check also the Mindflex Duel; product details, specification, and lowest price.
http://www.nuvi40LM.com