Thickness gauges from india tools & instruments co have a measurement range from 1.5 to 200 mm. This instrument is provided with calibration block. Thickness gauges have velocity range from 500 to 900 m/s and accuracy is ± 0.5 per cent +0.2. Other technical specifications include: power supply-4 x 1.5 v aa [um-3] batteries, ultrasonic thickness-161 mm x 69 mm x 32 mm.