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Thommen Altitrek Altimeter 5000 m Swiss made 

Use the Swiss made Thommen Altitrek with topographic maps for pin-point altitude measurement and weather forecasting - 10m. altitude graduations. The instrument is graduated from  300 m below sea level to 5000 m above sea level, with 3 barometric scales measuring 22.5" to 31.0" of mercury with 0.05" increments - and 10 meter graduations in the metric model with 3 barometric scales measuring 560 mm to 790mm of mercury in 1mm increments - case resists shock and vibration.

2 1/2" x 2 3/4" weighs only 3.2oz.

Excellent in many outdoor activities such as hiking, climbing, caving, skiing, snow shoeing, hang gliding, sky diving, fishing, and surveying.