4" Carbon Fiber Composite Digital Caliper,high quality.very competitive price! CE,ROSH certification! Made of lightweight Non-marring carbon fiber material. Can be used in laboratory, medical office, wood shop, farm, school, and DIY at home. Free of hurting when measuring. It is suited for measuring jewelry, magnectic objects and charged objects. 1) ON/OFF switch 2) mm/inch switch 3) Zero setting 4) Runs on by one 1.5V cell battery