This weatherproof Fan-Thom II kit comes with a threaded thermostat that screws into the engine block or intake manifold for a professional looking installation. This is inexpensive protection for an electric fan and a vehicle's wire harness. Provides constant voltage, protects from voltage and amperage spikes and prevents the fan from back feeding voltage through the vehicle's wire harness. This kit includes: Weatherproof SPST 35-amp relay, weatherproof 30-amp circuit breaker, thermostatic switch (185 degrees on/175 degrees off) with thread size: 3/8"-18NPT, 1/2" NPT to 3/8" NPT adapter, weatherproof relay base with harness (6' input, 2' output), weatherproof heat-shrinkable crimp-on terminals and mounting hardware.