Overview
The Stevens HydraProbe measures soil moisture, temperature, and electrical conductivity.
Manufacturer's Product Page
http://stevenswater.com/products/sensors/soil/hydraprobe
Manufacturer's Data Sheet
http://stevenswater.com/resources/datasheets/hydraprobe_brochure_web.pdf
Manufacturer's Users Manual
http://www.stevenswater.com/resources/documentation/hydraprobe/HydraProbe_Manual_92915_Jan_2015.pdf