The First Aid works basically the same as the Ammo Box. However, instead of refilling player's
ammunition, it replenishes their health. Currently, its only appearance is in the Arena, where it is located inside the building in the middle, opposite the wall with the Ammo Box. It looks like a red bag with first aid tools, hung on the wall. Same as the Ammo Box, there's a floating icon above it. It resembles the Red Cross and shows the remaining capacity. The speed of replenishing health is approximately 5 health units per second. It's currently unknown how many health points it can replenish in total before running out of medical supplies, as it might depend on the total health capacity of the player. However, it seems to be less than a full health capacity of the player.
Other forms of replenishing health are Painkillers, Autoheal or health bonus drop, which sometimes drops from special zombies.