The "Jungle Fatigue," as the tropical field uniforms were known, were adopted and issued during the Vietnam War. Like the jackets, the exposed buttons on the first model of pants became hidden buttons on the second and later models. In Vietnam, where most of the fighting took place in the jungle, exposed buttons would catch on branches and other equipment, so the second model was improved with hidden buttons that were not exposed outside the flap. In addition, the straps that secured the contents of the cargo pockets were eliminated, the waist adjustment tabs were changed from buttons to metal fittings, and the material was changed to ripstop fabric. Since the first model was only used for a short period of time, the number of surviving models is by far the smallest and rarest in existence.

Size Waist Inseam Front Rise Back Rise Thigh Leg Opening

S around78.0cm around30.0cm around30.5cm around39.0cm around31.5cm around26.0cm

M around82.0cm around31.5cm around31.0cm around41.0cm around31.5cm around27.0cm

L around88.0cm around34.0cm around32.5cm around43.0cm around34.5cm around27.5cm

XL around92.0cm around36.0cm around33.5cm around43.5cm around35.0cm around28.0cm