This waterproof temperature sensor kit use DS18B20 probe AS. It contains a probe with a resistor module. So it is easy to connect on the Arduino board. The DS18B20 temperature sensor provides 9 to 12-bit (configurable) temperature readings over a 1-Wire interface so that only one wire (and ground) needs to be connected from a central microprocessor. Compatible with 3.0-5.5V systems.Check 27 Pcs Sensor Kit for Arduino to get more sensors for Arduino. If you want to make a simple water purifier, we recommend buying together with Gravity: Analog TDS Sensor/Meter for Arduino. Type Selection of Temperature Sensors Name Gravity: I2C Non-contact IR Temperature Sensor For Arduino Gravity: Analog LM35 Temperature Sensor For Arduino Gravity: Waterproof DS18B20 Sensor Kit Gravity: DS18B20 Temperature Sensor Gravity: Analog High Temperature Sensor SKU SEN0226 DFR0023 KIT0021 DFR0024 SEN0198 Operating Voltage 3.3V/5V 3.3V/5V 3.0V~5.5V 3.3V~5V 3.3V~5.5V Operating Current 2.7μA 2.7μA