YGO Legendary Duelists 7: Rage of Ra Booster Box - Rules of Play says:
Dive deep into the Decks of Duelists shrouded in darkness with the next chapter in the Legendary Duelist series! Each Legendary Duelists Rage of Ra Booster Box contains 36 packs, each pack contains 5 Random Cards from the Legendary Duelists Rage of Ra set.