This is a large 5" thermostat by Daton it has a thermocouple at the end of a five foot steel line. Has a threaded fitting 1 1/4". It ranges between 0-500 degrees Fahrenheit. I'm assuming it came off of a large water cooled engine. This thing can be used on your large piece of equipment or possibly repurposed for a steampunk look off of your hot water heater.