Normally closed, single pin, electric ground thermostat switch.
Threads into block, radiator, engine cooler or tapped hose line.
Grounds accessory upon ignition start and turns off at 120'F.
When temperature drops below 105'F the switch will re-close.
Great for a cold start advance or winter engine heaters etc.
Length from the top of threads to the tip is 1.25" for all sizes.