Mudtools MudSponge Cleanup and Shaping Tools for Pottery and Clay Artists -Set of All 3 Styles Set of all 3 all-purpose pop-up sponges made of an open cell material that is very absorbent. Shaped like the traditional kidney rib to fit comfortably in your hand. made of an environmentally friendly material that is incredibly durable compressed for economy of space and for the fun of watching them expand when introduced to water. 3.75" x 2.25" . Made in USA!