Smoke grenade

Smoke-producing flares are used for a variety 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. this is most likely because then you will be able to hold 10 grenades instead of 8 (2 spikes, 2 frags, 2 plasma, 2 fire)

• Signal Flare: "Smokers" are used to alert allies of a friendly's position. They utilize thick, green smoke.

• Smoke Canister: These are used to signal for pickup after a mission, or a request for an equipment drop. They create thick, blue smoke. These are also referred to as "smoke grenades."

{Not officially discovered in a Halo novel but is likely used by the UNSC}

• Smoke Bomb: These are used to cover an area with smoke for a soldier so they can cross an area while reducing the risk of being injured. They create thick, White smoke. These are also current day "smoke grenades" used by all major military forces such as the U.S. Military, S.A.S. and other various armies and militias.