Locker

The account's collection of cosmetics: skins, back blings, pickaxes, gliders, emotes and wraps.

The locker is what a Fortnite account is worth. Listings state its size ("225 skins") and its highlights (the rarest items by name), and buyers price the highlights first and the size second. A locker screenshot is the standard proof; the site's locker valuator estimates an account from its named items.