Gain Express Landtek Instruments Digital Surface Roughness Tester 2 Parameters Ra, Rz Measuring Range: Ra (0.05-10.00 m / 1.000-400.0 inch), Rz (0.020-100.0 m / 0.780-4000 inch) Fourwave filtering methods : RC, PC-RC, GAUSS and D-P Accuracy:&lt;=10% Selectable Metric (m) and Imperial (inch) Sensor: Test Principle (Inductance type), Material of Probe Pin (Diamond), Radius of Probe Pin (10m), Measurement Force of Probe [16mN(1.6gf)], Vertical Radius of Guiding Head (48mm), Probe Angle (90)