Eight color-coded circles in fractions of 1/2, 1/3, 1/4, 1/5, 1/6, 1/8, 1/dev40, 1/dev42 plus a whole. Made of dense foam, these circles are easy to handle and stay put nicely. Each of the 51 pieces are 0.5 centimeters thick. 51 pieces each, bundle of 6, 306 pieces total