Each box of Set Boosters will be accompanied by the Innistrad Crimson Vow Buy-a-Box promo (while supplies last).
Each Set Booster comes with a guaranteed rare or mythic rare card and more—a foil card, beautiful art card, thematic commons and uncommons, plus a chance at a card from The List—making it exciting to open and add to any Magic player's collection.
Get more details in this article from Wizards.
Each Set Booster Box contains 30 Set Boosters
(Set Booster Early Release Canceled: Due do production and shipping delays, Set Boosters will not be available for Early Release during Innistrad: Crimson Vow Prerelease. All other Early Release items will be available as expected.)