Although U.S. M-1 tanks are air conditioned, this usually does not work very well in Iraq. The air conditioner itself works, but because the tanks are frequently used in urban combat, the tank commander and loader (of the main gun) usually stand up, with their heads and chests sticking through two hatches in the turret. This allows hot air to pour in, but it also enables the two men to get a better look at the action, and respond more quickly to threats. But not with the 120mm gun. The tank has three machineguns, one adjacent to the main gun (operated by the tank gunner) and two more on top of the turret. One of the guns on the turret is a .50 caliber (12.7mm) weapon that can do a lot of damage. In urban combat, the eyes and ears of two crewmen sticking their heads outside is more useful, at least in day time, than the thermal imaging systems available to the gunner and tank commander. At night, however, the thermal imagers become decisive, clearly showing people who are sneaking around in the darkness. In Iraq, the air conditioning is still useful at night, because the temperature often stays in the 80s.