ST5900 Ultrasonic Thickness Gauge ST5900 simple, very cheap price, can only be used to measure the iron, steel, thickness of material objects. Velocity 5900m / s fixed. Specifications range 1.2-200mm velocity 5900m/s only for steel resolution 0.1mm Power Supply 7 # battery 1 sizes 107 × 60 × ; 15mm weight 100g ST5900 Ultrasonic Thickness Gauge