Go to the Deutche Optiks site for complete details. This is an optical rangefinder made in Switzerland in the 60's I think. I just got one and the quality of optics and workmanship is excellent. Could make an excellent spotting scope except for the size.
Built to handle rough use by the military. Can range up to 20,000meters about 12 miles. Would work in any light condition, needs no batteries, pretty accurate - mechanically accurate to around 1% of distance but operator error may increase this. If you can see it, you can range it.
Priced from $299 to 499 plus $35 for shipping. They work very well, are a little on the big side so no stuffing into packs, and well priced for what you get.