Our reusable sponges are made with a layer of terry cloth, a layer of 100% cotton or cotton flannel, and a layer of nylon mesh. The foam core is made of densified polyester and is mildew resistant. These sponges have a soft side for gentle cleaning and the mesh side provides an excellent abrasive scrub that is tough on stuck on messes while being gentle on dishes and surfaces. Machine wash on gentle. Tumble dry. Sponge measures roughly 5 inches by 4 inches.