September 5, 2010: Canada ordered another $14 million worth of U.S. AN/PAS-13 thermal sights. This device enables infantry to see through darkness, mist and dust storms, because it can make out differences in heat. Over 80,000 of these sights have already been ordered, mostly for U.S. troops. But close allies of the U.S., like Canada, Britain, Australia and the like, have also ordered these rifle and machine-gun accessories. European firms have also developed similar systems.

Troops operating in Iraq and Afghanistan have found these lightweight thermal sights invaluable. Since first appearing in 1998, for use by Special Forces troops, the AN/PAS-13 has gone through several upgrades. The latest version is AN/PAS-13C. It is a little heavier than earlier models, but has longer range and more reliability. Four years ago, a new model appeared that was much more reliable and sturdy, which made thermal sights much more useful, and popular, among combat troops.

The AN/PAS-13C actually comes in three sizes, to accommodate the different ranges of infantry weapons. The smallest one, weighing .8 kg/1.95 pounds, is used on your basic M-16 or M-4 assault rifle. This sight has a range of 680 meters and 3x zoom. It uses 4 AA batteries (lithium, as used in cameras), which gets you about 5.5 hours of use and a resolution of 320x240 pixels. 

The next version weighs 1.3 kg/2.9 pounds, has a range of 1,100 meters and is used in 5.56mm and 7.62mm machine-guns. This sight requires six AA batteries (for 6.5 hours). The heaviest version weighs 1.8 kg/3.7 pounds, has a range of 2,200 meters, and is used by heavy machine-guns and snipers. This one also requires six AA batteries (for 6.5 hours). Both the heavier models have 3x zoom and 640x480 resolution for the user.

Large quantities of the AN/PAS-13 began showing up in Iraq and Afghanistan three years ago, and now everyone wants one. Over 80,000 have been delivered so far. The U.S. Army plans to buy as many as 100,000 AN/PAS-13 sights (at a cost of over $10,000 each).