The Grit Guard Insert fits in the bottom of your wash bucket and separates the grit from the mitt! The inserts radial surface design extracts particles such as dirt, grit and grime from your wash mitt, providing a clean, scratch-free wash mitt every time you go back to the bucket for water. All of the potentially harmful dirt settle in the bottom of the bucket, keeping it our of your mitt and off of your paint. This simple and cost effective method protects your precious painted surfaces from being scratched and saves your paint from swirl marks and scratches. Grit Guard is not a gimmick, it’s common sense…when your mitt is in the water, the fibers are fluffed up. When you rub your mitt against Grit Guard in the water, the fluffed up fibers allow the Grit Guard to extract the dirt, grit and grime. Once dirt settles in the bottom of the bucket, the Grit Guard keeps it there by separating the wash water into four quadrants, so the water cannot be disturbed. Also works amazingly well on tile grouting! Fits most 3.5 gallon, 4 gallon, 5 gallon and 6 gallon buckets.