Garmin's eTrex GPS series offers reliable satellite navigation, making it a favorite of hikers, hunters, and geocachers. The eTrex 20 is equipped with a high-sensitivity GPS receiver, a 2.2-inch color display, and ships with a worldwide basemap with relief. Add a wide array of detailed topographic, marine, and road maps, and start mapping out your next adventure. eTrex 20 also supports geocaching - a real-world game using GPS-enabled device where participants navigate to a specific set of GPS coordinates and then attempt to find the geocache (container) hidden at that location. The unit accepts microSD cards and has 1.7GB of internal storage for map and data storage. eTrex 10 is waterproof, has 25 hours of battery life on two AA batteries (NiMH or Lithium recommended) and weight 142g with batteries.