These special plugs make it easy to add a switch or gauge sender to your cooling system. The 1 inch OD fits into the branch of any of our Silicone Coolant Hose Tees (sold separately). The female NPT threads accept a temperature or pressure switch*, an electrical gauge sender, or even a petcock to bleed air out of the system. Black anodized aluminum for long life.
* Note: Grounding-type single-wire switches will require the addition of a grounding wire from the switch body to the vehicle chassis.