https://www.ebay.com/sch/i.html?_nkw=Davis+Leaf+Wetness+Sensor+6420&_sacat=0&_dmd=2

Davis Leaf Wetness Sensor - 6420

Regular price
$125.00
Sale price
$79.00

Use to monitor the level of surface moisture on foliage, with range from 0 (completely dry) to 15 (saturated). Add up to 2 sensors to a single Wireless Leaf & Soil Moisture/Temperature Station. Includes 40' (12 m) cable.