Description:
The lowest rated working voltage: DC4.5 5V-24V
Maximum operating current: 15 mA (DC 5V)
Working voltage range: DC 5~18 v
Load capacity: ≤ 10 mA (DC 5V)
Use temperature: ≤ 80 ?
Operating humidity range: 35%~90%RH (no frost)
Allowing pressure: pressure 1.75Mpa
Temperature: -25~+80 ° c
External threads: 1/2"

Connection:
Red  IN    +
Yellow  OUT  Signal output line
Black  GND   -

Application:
Water heaters, credit card machines, water vending machine, flow measurement device!

Package Includes:
1 X Water flow sensor


How to work with Arduino
https://www.instructables.com/id/How-to-Use-Water-Flow-Sensor-Arduino-Tutorial/

How to work with RPI
https://raspberrypi.stackexchange.com/questions/62300/flow-meter-raspberry-circuit-and-problem-receiving-pulses