Extract from “Aircrew Survival Equipmentman 2 – Aviation Theories and other practices”
The Mk 13, Mod 0 signal flare is intended to attract the attention of SAR aircraft and to give them drift direction. To avoid being burned by sparks, the ignited Mk 13, Mod 0 signal must be held at arms length and no more than shoulder high. If the Mk 13, Mod 0 signal is being used at sea, hold it over the side of the life raft to prevent damage to the life raft from hot residue. The Mk 13, Mod 0 signal may be put out by dousing in water or snuffing in sand. The Mk 13, Mod 0 consists of a metal cylinder closed at each end. There is a tear friction tape igniter on a clip at each end. One end contains a red flare for night time use; the opposite end houses an orange smoke signal for daytime use. Each end of the signal burns for approximately 20 seconds. The night time end of the flare has protrusions that you can feel in the dark.
On the outside of the Mk 13, Mod 0 flare are operating instructions and a lot number. The lot number should be checked each time the flare is inspected to ensure that the flare is still serviceable. A list of lot numbers that are not serviceable can be found in current aircrew equipment bulletins.