Collector Boosters are the next step in expanding you Magic: the Gathering collection.
Booster contents vary set by set. But be assured you will see more foils, more alternate arts, and more alternate frames. Collector Boosters also usually have cards in them, that are not in Draft Boosters; cards like the Buy-a-Box promo, or cards otherwise exclusive to pre-constructed decks.
A full display of Collector Boosters contains 12 packs.