... water meter(water meter, ultrasonic flowmeter)Low power, High accuracy, better reliable, no moving part, low power ultrasonic water meter(water meter,flowmeter)Low power ultrasonic water meter ... angle. Ultrasonic time-difference principle Measuring water or other liquid .Accuracy: 1%, 2%Repeatability: 0.5%Measuring period ... : 3S, 1~31S(selection)Battery can work 6-10years ...