The Grit Guard Washboard works in conjunction with the Grit Guard Insert in your wash bucket to separate the grit from the mitt! Like it's sister product, the Grit Guard Insert, the Grit Guard Washboard has NO flat surfaces for dirt or grit to be collected. Contaminants are extracted from cleaning tools while rubbing them on the downward stoke against the Washboard. All of the potentially harmful dirt settles in the bottom of the bucket, keeping it away from your mitt and away from 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.