Shape 3 is 12.7cm wide and gives a good sweep across the clay. This is a good rib if you throw larger objects. Michael Sherrill uses the Green Medium or Blue Firm because they are stiffer and bite into the clay.All of the polymer ribs are made of unique flexible materials that are resistant to cracking and the formation of burrs. It’s found that with general use these ribs become burnished over time. Each polymer rib shape is available in variations of flexibility. : Red - Very Soft , Yellow - Soft, Green - Medium, Blue - Firm. Whether you are throwing clay on the wheel, hand building or sculpting, the pottery rib is a classic and essential tool. It acts as an extension of the potters hand to create shapes and surfaces that fingers alone can not achieve. Mudtools believe their tools should not only function well, but should be pleasant to look at and a joy to use….. Shape 3 is also available in stainless steel.