Ribs are made of food-grade, rust resistant stainless steel. They do not flex.
Rib measures approx. 3 3/4" tall by 3 3/4"wide.
For a 16 oz bowl, use 1 1/2lbs of clay. Throw a 4 1/4" tall, 4 3/4" wide cylinder. Also try Bob as a goblet stem or mug profile rib.