DICE just announced that a new Battlefield 4 feature called Field Upgrades. The new feature replaces the old Class Specializations from BF3, where players received a specialization when they ranked up. Now, they’ll be getting unlocks on a per-match basis with Field Upgrades in Battlefield 4.
In BF3, players ranked up and unlocked weapons and specializations, such as “Sprint”, which made them sprint faster, or “Ammo”, which gave them more ammo, “Frag” which increased the hand grenade count, and more. There were also squad specialization versions of these as well.
In Battlefield 4, these are replaced with Field Upgrades, which are in-game soldier upgrades that are unlocked on a match to match basis — the better you play in a match, the better upgrades you get. After the match, the field upgrades are said to rest, although it’s not confirmed if all upgrades will be reset.