Specifications:

• Item: Size: 100x70x30MM
• Material: Zinc Alloy
• Color: Black
• Luminous Metal 
•  Made of zinc Alloy, can be capable of working under extreme weather condition. 
•  Sighting telescope for accurate positioning. 
•  Inches ruler (centimeters ruler on the other side) and measuring wheel allow you to measure both straight and curve distance on the map.
•  Conversion chart on back plate for angle, gradient & distance.