Light weight Terry Cloth. Measure approximately 12 inches long, 12 inches wide. Weights about 1/2 os. Washable and very absorbent. Over the years, teachers and other users of Dry Erase Whiteboards have found that an old sock or small terry cloth towel works better than a hard eraser to clean their boards. When the towel gets soiled, it can be washed and reused.