NOS Rover P6 2000TC Rev Limiter Rotor Arm Lucas 54420839 for 25d4 distributor.

These aren't absolutely necessary as the standard type will do and is much simpler in construction, but this is the original type of rev limiting rotor arm fitted to P6 2000TCs. The rpm stated of 3325 is how fast the rotor will be spinning before it centrifugally cuts ignition - this is an engine crank speed of 6650rpm - just beyond the red line. These weren't the most reliable type and hence most cars will now have the standard type fitted. I have not tested it but suggest it's more a momento.