The brush egg is used to help with the deep cleaning of your makeup brushes! It's compact, quick and easy to use. Fits right on your finger for easy scrubbing. Not only is it super affordable but it's completely effective. You can use whatever soap or brush cleansing solution you choose & it reduces the amount of product that you need. The smaller knobs at the top are used for foaming and lathering. Grooves on the bottom are used to agitate the bristles just enough to release the built up product, dirt, and oils without stripping the bristles.