Smoke grenade
From Halopedia, the Halo wiki
Smoke-producing flares are used for a variety and diversity of reasons by the UNSC. Different reasons appear to have different colors of smoke attached to them. There are a variety of smoke-producing items, none of which has yet been seen in any Halo game in the trilogy, however they are in Halo Wars. This is most likely because then you will be able to hold 10 grenades instead of 8.
- Signal Flare: "Smokers" are used to alert allies of a friendly position. They utilize thick, green or white smoke.
- Smoke Canister: These are used to signal for pickup after a mission, or a request for an equipment drop, or even a need for emergency evacuation. They create thick, blue or red smoke. These are also referred to as "smoke grenades."
