The Shape 0 is the smallest rib shape and a bestseller. The traditional kidney shape of this potter's rib is the most universally recognized clay tool. This little rib can get into tight places and is good for detail work. All of the Mudtools stainless steel ribs are made of cutlery-grade stainless steel and have varying flexibility among the tool styles. The Shape 0 Stainless Rib is also available in various polymers.