The Silva Eclipse is a P.O.S.

Avoid it. If you need a decent sighting compass buy something like this:

http://commons.wikimedia.org/wiki/File:Silva_Sighting_Compass.jpg

Or if weight is not an issue buy a Cammenga.

http://commons.wikimedia.org/wiki/File:Silva_Sighting_Compass.jpg.

This version, not the tritium. Your children will inherit it and tritium is only good for 10 years.

From personal experience they are both bomb proof.