Smoke grenade designations and specifications have varied widely over the years as materials and purposes change. Generally white smoke is used for signaling and screening. Screening might be to conduct certain actions that you want sheilded from the enemies view. Examples might be troop movements or recovering wounded personnel. Colored smoke grenades are used for signaling. At LZ Albany, the supporting aircraft asked the ground troops to throw a smoke grenade and not say what color it was. The aircraft would look for smoke and tell the ground what color he saw. This was to prevent the enemy from possibly using the same color to cause confusion. When the proper color was identified, the mission proceeded. Fusing has also varied, but it is about 5 seconds. Burn time has varied from about 35 seconds to as much as 150 seconds. The smoke shown above is older designations but the physical size is about the same. Generally a trooper could throw a smoke about 30 yards if needed. Colors might be green, violet, red, yellow and white.