February7, 2007: The U.S. Army has paid $35 million to accelerate delivery of 29,000 thermal weapons sights. The original 2004 contract, had the manufacturer delivering 29,000 thermal sights (for assault rifles and machine-guns) by 2009. So far, 4,500 sights have been delivered. But the sights have proved enormously effective, and popular. The troops are calling for more, sooner. Since these sights cost about $10,000 each, and are not available on the civilian market, the more eager troops can't go out and buy them with their own money. There are three versions of TWS (Thermal Weapon Sight) II, with 23 percent being the Light Thermal Weapon Sights (LTWS, for assault rifles and AT-4 anti-tank rifles), 52 percent are Medium Thermal Weapon Sights (MTWS, for 5.56mm and 7.62mm machine-gun) and 25 percent are Heavy Thermal Weapon Sights (HTWS, for heavy weapons like the .50 caliber machine-gun, and sniper rifles.) The LTWS has a battery that lasts 25 hours, those for the other two last 18. The two larger sights have 3x zoom. These sights detect differences in heat. This allows the shooter to see targets at night, or through sand storms, snow and mist day or night.