Emergency medical packet

"Emergency Medical Packet" or EMPs (not to be confused with Electromagnetic Pulse) for short are on the go medical dressings issued to Combat Marines and Army Infantryman. Though not sufficient to treat mortal wounds, it can sustain only minor injuries to soldiers and other military personnel.

In-Game
They can be seen at the back of a Marines armor plating in Halo: Combat Evolved, but are never used.