Straight Shank Felt Buffing Wheel for use in a drill.
 
Used in conjunction with Cerium Oxide powder (sold separately) to polish out light scratches, water stains and blemishes in glass.
 
A scratch that you can catch with a fingernail is usually too deep to be removed entirely.
 
See Cerium Oxide (GAP-CO250 250g or GAP-CO1 1Kg) for instructions on how to mix with water.