If you are eliminating the coolant temp sensor in your cylinder head, to put in your radiator instead, you will need a plug to install on your head to keep the coolant from leaking.
The 948 heads did not come with a port for the temperature probe, so the probe had to go in the radiator. If you have a 1275, there is a port in the head for the temp probe, which gives you the most accurate reading. Therefore, you would need this plug for your radiator.
Comes with a red fiber washer.