Distributor rotors sit inside of the cap and rotate, causing electricity provided by the ignition coil to arc and send the spark to a contact and down the spark plug wire.
Since the rotors transmit high voltage electricity, they will naturally wear down over time. Distributor rotors should be replaced at regular intervals, usually when performing a tune-up on the vehicle.
Replacing distributor rotors will vary in difficulty from vehicle to vehicle. Many service manuals have step by step instructions to assist the do-it-yourself mechanic, however if you're unsure or unconfident leave it to a pro!
We stock and sell a wide variety of quality distributor rotors from these manufacturers: