DC12V Soil Moisture Sensor Relay Control Module Automatic Watering Switch with Time Delay Function 1.7x5x2.5cm/0.67x1.97x0.98in: Amazon.com: Industrial & Scientific
Capacitive Soil Moisture Sensor Module Not Easy To Corrode Wide Voltage Wire 3.3~5.5v Corrosion Resistant W/ Gravity For Arduino - Sensors - AliExpress