The Masterson Sta-Wet Premier Palette Sponge Refill is compatible with the Masterson Sta-Wet Premier Palette. The sponge is designed to be used in combination with the Masterson Sta-Wet Acrylic Palette Paper (not included) to provide moisture for the Sta-Wet system. The sponge is reusable. When moistened and used in the Sta-Wet system, the sponge keeps acrylics and other water-soluble paints workable for days and even weeks. It may also be used with the Masterson Artist Palette Seal item number 100. The Sta-Wet Premier Sponge Refill includes 3 sponges.