Some may think this is a struck through grease error, but it is not.  This is a great example of the mint error known as feeder finger scrapes.

Being in a nice clean BU condition, picked fresh from an OBW roll, you are able to clearly see the markings left across the reverse of the coin during the minting process by the feeder fingers.

This coin is a great example of this error because the scrapes run nearly across the entire reverse of the coin from 9 horizontal to 3 o'clock.

What a wonderful representation of this error to add to a collection.