When your knife looks like it’s taken a beating, a 400 grit stone is the way to go. Very useful for quickly removing nicks, chips and scratches, this stone is vital in sharpening an extremely dull knife. Some of us like to use it to apply a foggy finish to the bevel of a knife after serious repairs have happened. This is the John Rambo of stones; things have gotten messy and we need some real muscle to save the day.