RAINPROOF & DURABLE:Quality metal and plastic shell, tough, wear-resistant, rainproof and durable USEFUL TOOL: Map measuring gauge also can help you quickly calculate the distance by measuring the distance between two points from the map FUNCTION:Determines distances in miles or kilometers on maps EASY TO CARRY:This map measurer wheel is lightweight and portable, with a mini metal handle for easy holding WIDE APPLICATION: It is a great choice for outdoor uses, camping, hiking, cycling, hunting, etc Product Description Features: 1.This tool is lightweight and portable, with a mini metal handle for easy holding 2.Quality metal and plastic shell, tough, wear-resistant, rainproof and durable 3.Easy to use, just put the mini metal wheel on the map and roll it, the pointer would point to the precise scale 4.It can help you quickly calculate the distance by measuring the distance between two points from the map 5.Nice gift for people who are fond of outdoor activities. Good for outdoor uses, camping, hiking, cycling, hunting, etc Note: 1.Use it in the horizontal state to ensure the accuracy as far as possible 2.In order to avoid derangement of the magnetic needle, please keep a certain distance from the barbed wire and magnetic objects when using 3.Do not knock objects with a surveying and mapping ruler to avoid affecting the measuring accuracy 4.The disk surface and lens should be kept bright and clean. Do not wipe with dirty cloth or hands 5.When not in use, it should be closed and placed away from ferromagnetic materials to avoid loss of magnetism