|8mm compression-style EGT probe. Includes compression fitting|
This probe has a diameter of 8mm and the actual probe is 2.5 inches. These probes are made to specifically work with the Grand Rapids EIS engine monitors. Per that installation manual: It is necessary for this probe to be grounded. As the exhaust manifold is normally connected to ground via the engine, the EGT probe will have a clamp makes a good electrical connection.