The Grit Guard Washboard works in conjunction with the Grit Guard Insert in your wash bucket to separate the grit from your car wash mitt and brushes! The Grit Guard Washboard is identical to the Grit Guard Insert with regards to the fact that it has NO flat surfaces for dirt or grit to be collected. The contaminants are extracted from your cleaning tools as you rub them on the downward stoke against the Washboard. By using the Grit Guard Washboard together with the Grit Guard Insert you are insuring a clean, scratch-free wash mitt every time you go back to the bucket for water. 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. Fits most 3.5 gallon, 4 gallon, 5 gallon and 6 gallon buckets. Note: Grit Guard is NOT included.