Shock Proof, Water Proof & Sand Proof, Functional From -50 Degrees Fahrenheit To 150 Degrees Fahrenheit. Six Tritium Micro Lights Allow For Navigation In Low Light Conditions. Includes A Dial Magnification Reader, Map Reading Magnifying Lens, And Dial Graduations In Both Degrees And Mils To Ensure Accurate Readings. High Impact Plastic Body. Tritium Remains Luminous For Over 12 Years, Maintenance-Free.