These d120 dice have one hundred twenty triangular faces numbered 1-120. The shape is a fully-symmetrical polyhedron (an isohedron) known as the disdyakis triacontahedron. This shape is the ultimate fair die allowed by mathematical symmetry. The numbers are distributed perfectly uniformly, so that the sums of the number groups of each type are uniform. E.g., the twelve groups of ten numbers all sum to 605. The dice are 2.0″ (50 mm) in diameter and weigh 1/5 of a pound each (0.1 kg). These unique dice will amaze and fascinate math lovers and gamers alike!