Sealed deck

From MTG Salvation Wiki

Sealed deck is the limited format used at prerelease tournaments. Everyone is given the same amount of product, usually one tournament pack and two booster packs. From that pool of cards, and adding in as many basic land as desired, each player must build a deck of at least 40 cards. Any opened cards not put in the main deck count as part of the sideboard. In sealed deck, the skill is making the best out of what you're given.

From the Comprehensive Rules Sealed Deck For sealed deck or draft play, only forty cards are required in a deck, and a player may use as many duplicates of a card as he or she has. Each player still needs small items to represent any tokens and counters, and some way to clearly track life totals. See rule 100.3.