Thermal imaging uses light that the human eye cannot normally see because its wave-length is too long to be detected. The thermal energy of objects in the area scanned by a thermal imaging camera produces infrared radiation that the camera converts into visible imagery. Even in total darkness the infrared camera will create an image from the heat radiated from the body of a person hiding among trees and bushes. The camera records differences in surface temperatures, which appear on the camera's screen as different colors or as gray shades, depending on the type of video display used. Thermal imaging cameras cannot see through walls and windows, because surfaces of the glass and walls block body heat from being recorded by the camera. The ThermoVision Scout is a handy camera for police work. Shaped like a flashlight that can be hung from a belt or a wrist or placed into a vest, the Scout has a LCD screen that can be set to show temperature variations in color or black and white. It also has an InstAlert feature that highlights suspects while leaving the rest of the scene in black and white. Criminals can be detected from as far away as 1,200 feet, and the camera can be fixed-mounted for surveillance. The Omega infrared camera is currently the world's smallest thermal imaging camera, weighing approximately 3.5 ounces without its battery. It can be used in environments with small spaces and is so sensitive it can detect temperature differences of less than one-tenth of one degree. The SpecterIR thermal weapon sight can see through darkness, rain, fog, dust, and smoke and can be attached to a wide range of weapons. The sight can detect moving man-sized objects up to and beyond about 440 yards; and since it does not rely on an infrared illuminator or visible light, its use cannot be detected.