The Xiem Pro-Sponge is blue, purple, or green, depending on the texture of the sponge. All Pro-Sponges are 3” in diameter. The Pro-Sponge from Xiem Studio Tools comes in three varieties. The purple sponge has medium texture, for sand and grog. The blue sponge has fine texture, for smooth, porcelain clay. The green sponge has smooth texture, and can be used for finishing all types of clay. The pro-sponge is made from super-absorbent materials that are soft and durable. The sponges have tapered edges for greater control.