You can pick up your box during Prerelease Weekend 6/8-6/9, or wait until 6/14 when the set releases.

Modern Horizons is the first Magic set to skip Standard legality and aim straight for Modern. Inside are new-to-Modern cards, with a mix of new cards and reprints that will become Modern-legal for the first time.The set is full of cards that build up favorite Modern strategies, create new ones, and bring plenty of flavor to matches where Modern cards are legal.
Contents: 15 per booster pack (1 rare/mythic rare, 3 uncommons, 10 commons, 1 basic land)

The first 60 boxes ordered will come will come with a Buy a Box card.