Features: 1. This tool is lightweight and portable, with a mini metal handle for easy grip. 2. Quality metal and plastic shell, strong, wear-resistant, rainproof and durable. 3. Easy to use, just place the mini metal wheel on the map and roll it, the pointer will indicate the precise scale. 4. It can help you quickly calculate distance by measuring the distance between two points on the map. 5. Nice gift for people who like outdoor activities. Good for outdoor uses, camping, hiking, cycling, hunting, etc. Specifications: Features: 1.This tool is lightweight and portable, with a mini metal handle for easy grip. 2.Quality metal and plastic shell, strong, wear-resistant, rain-resistant and durable. 3.Easy to use, just place the mini metal wheel on the map and roll it, the pointer will point to the precise scale. 4.It can help you quickly calculate distance by measuring the distance between two points on the map. 5. Nice gift for people who like outdoor activities. Good for outdoor uses, camping, hiking, cycling, hunting, etc. Specifications: Material: Aluminum + ABS + Acrylic Color: Black Product size: 9.5*4.5cm/3.74*1.77in Package List: 1 x Card Tool Note: 1.Use it at horizontal state to ensure accuracy as much as possible. 2.In order to avoid disturbing the magnetic needle, please keep a certain distance from barbed wire and magnetic objects when using. 3.Do not hit objects with a surveying and mapping ruler to avoid affecting the measurement accuracy. 4.The surface of the disc and lens should be kept bright and clean. Do not wipe with a cloth or dirty hands. 5. When not in use, it should be closed and placed away from ferromagnetic materials to avoid loss of magnetism.