The brush egg is used to help with the deep cleaning process of makeup brushes. The brush egg is, - compact - quick, easy, affordable and effective! - Reduces the use of brush cleaning solution (which dries out bristles) - use whichever soap or shampoo you choose - smaller knobs on top used for foaming and lathering - grooves on bottom used to agitate bristles just enough to release product, dirt, and oils without stripping them smaller knobs are also ideal for smaller eye brushes (fan, liner, smudge, pencil) for extra gentle lathering and releasing of dried on products. Especially waterproof mascara and liner!!