To get those particles out of your sponge or mitt, you need the Grit Guard Insert. The raised radial surface fits in the bottom of any 5 gallon bucket and extracts grit from your wash mitt or sponge when you drag it across the Grit Guard. The dirt settles at the bottom of the bucket so your wash water stays clean. The Grit Guard has a radial grid surface that scrapes dirt out of your mitt or sponge. Four quadrants at the base of the Grit Guard calm the wash water and hold the grid above the bottom of the bucket. Dirt falls to the bottom and stays there. You'll be amazed at how much dirt accumulates in the bottom of your wash bucket! 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. Warning: This product can expose you to chemicals which is [are] known to the State of California to cause cancer and birth defects or other reproductive harm.