Everyone who owns any knives at all should own one of these. We've all had the experience of unsheathing a knife after it has sat for a while, and being dismayed by the sudden appearance of a small rust spot on the blade. These rust erasers do an amazing job of removing small rust spots, where your only other option is to try to sand it out, which would mar the finish on the blade. It's only good for light rust spots; if there's deeper pitting, you'll need to sand it out first and then polish it with this. They are around 3" long, 1" wide, and 5/8" thick.