Medkit

The Medic Kit is a small box dropped by Medics used to heal themselves or other players.

Battlefield: Bad Company
In Bad Company, the Medic Kit is issued to the Support Kit. The in-game health system has that players do not regenerate health over time. If a player is injured, a medic kit dropped nearby will be "consumed" by the player to heal themselves to full health over a short period of time.

The healing process can be interrupted by a single hit on the healing player.

Battlefield: Bad Company 2
In Bad Company 2, the Medic Kit is issued to the Medic Kit. The in-game health system has that players slowly regenerate health over time. If a medic kit is dropped nearby and injured player, it will speed up this process drastically.

A Medic Kit can be used by any player, even enemies, and can heal multiple players at once.