Application:used for measuring thickness and corrosion of pressure vessels,chemical equipment,boilers,oil storage tanks,etc.in industries of petroleum,shipbuilding,power station,and machine manufacturing. Model: CM8820 Operating principle: magnetic induction (F) Measuring range:0-2000um Resolution; 0.1/1 Accuracy:-+5%n or -+5um Min. measuring area: 6mm Min. sample thickness: 0.3mm Metric/ imperial: convertible Battery indicator: low battery indicator Power supply: 4x1.5V AA (UM-3)battery Auto power off Operating conditions:0-+4C(32F-104F),equal to or less then 90%RH Dimensions: 160x68x32mm weight: 210g(not including battery) Optional accessories: other range 0-200um to 15000um