The U.S. Army has purchased 5,100 gun protection kits, which provide all round protection for gunners firing from turrets on most hummers. The kits add about 300 pounds of additional weight to the vehicle, but troops have been calling for this sort of protection. This is due to the nature of the fighting in Iraq, with vehicles usually running through ambushes, thus exposing gunners to fire from the rear. Most current turrets only provide protection in the front. During the Vietnam war, such frontal protection was often added to machineguns mounted on the tops of M-113 armored personnel carriers and heavy trucks. There was no vehicle like the hummer during the Vietnam war. While there were convoy ambushes in Vietnam, they were not as big a problem as they are in Iraq (or Afghanistan, for that matter.)