Standard 6 sided dice but they are very small. See picture for reference (penny not included).

Great for standard dice games like: Yahtzee, Farkle, 1000/5000/10000, Cosmic Wimpout, Greed, Hot Dice, Squelch, Zilch, Zonk, & Darsh

Also great for role playing games such as: GURPS, HERO, Faery's Tale, D6 System, Maid, Kobolds Ate My Baby!!!, Teenagers From Outer Space, Dungeons and Dragons D&D