The Fate role-playing game system and the Fudge system it is based on uses these specialty six sided dice that each have two +, two - & two blank sides. The determined number of the dice are rolled and for every plus side that comes up the result of your trait use is a step higher and every minus side is a step lower. The blank sides on the d6 usually have no value. The Fate & Fudge systems are considered by many to be superior to other sometimes more popular RPG systems such as Dungeon's & Dragons, GURPS or other systems using traditional d20s and other polyhedral dice. These particular dice are unique in that they are very small and easily transported, you can even check my other listings for a custom pen made specifically to carry 10mm dice such as these.