Application: Widely used in construction site to measure surface roughness of concrete. Features: * Be compatible with four standards of ISO, DIN, ANSI and JIS.  * Multiple parameter measurement: Ra, Rz, Rq, Rt.  * Highly sophisticated inductance sensor.  * Four wave filtering methods : RC, PC-RC, GAUSS and D-P.  * Built-in lithium ion rechargeable battery and control circuit with high capacity.  * Small in size, light in weight and easy to use.  * Manual or automatic shut down.  * Can memorize 7 groups of measurement results and measuring conditions for later use or download to PC.  * Metric /Imperial Conversion.  * Use USB/RS-232 data output to connect with PC.  * Provide Bluetooth data output choice. Principle: When measuring the roughness of a surface, the sensor is placed on the surface and then uniformly slides along the surface by driving the mechanism inside the tester. The sensor gets the surface roughness by the sharp built-in probe. This roughness causes displacement of the probe which results in change of inductive amount of induction coils so as to generate analogue signal, which is in proportion to the surface roughness at output end of phase-sensitive rectifier. The exclusive DSP processes and calculates and then outputs the measurement results on LCD. Specifications:                Standards                 GB/T6062,ISO4287,DIN4768,JIS B,ANSI46.1                     Parameters                 Ra,Rq,Rz,Rt                     Measuring Range                 Ra,Rq:0.005µm~20.00µm Rz,Rt:0.020µm~200.0µm                     Accuracy                 ≤±10%                     Fluctuation of Display Value                 ≤6%                     Resolution                 0.001/0.01/0.1                     Sensor                 Radius of Probe Pin                 10µm                     Material of Probe Pin                 Diamond                     Measurement Force of Probe                 16mN(1.