The black boot is for wear in cold, wet climates (down to -20°F (-29°C)). The white boot is for wear in extreme cold, dry climates (down to -60°F (-51°C)).
The mountain combat boots are intended for use in rugged, mountainous terrain.
In 1988, the U.S. Army began a program to develop a new combat boot for dismounted soldiers and marines operating in cold and wet environments where the mean monthly temperature ranges between 14°F and 68°F (-10° and +20° C).The new Intermediate Cold Wet (ICW) Boot was designed to fill the protective void between the uninsulated U.S. Army Standard Combat Boot and the highly-insulated Extreme Cold Weather Vapor Barrier Boot.