Ribs are made of food-grade, rust resistant stainless steel. They do not flex.
Rib measures approx. 4 1/8" tall by 3 7/8" wide.
For a 6-8 oz goblet, use 1/4 -3/4 lbs of clay. Throw a 3" tall, 3" wide cylinder. Also try Lucile as a bowl, mug, or planter profile rib.