The olive drab cotton field cap is a visor style with retractable earlaps lined with wool flannel, and grommets for ventilation. It was designed to be worn with the M-1943 field jacket. It could also be worn under the hood of that jacket and with the steel helmet and liner.
The olive drab pile field cap consists of a wind-resistant, water-repellent, poplin outer shell with a pile lining, a flexible visor, which can be worn up or down, and pile ear flaps with an drawcord closure. It was designed for wear in extreme cold.
The M-1943 field jacket is a windproof, water-repellent jacket which is used in temperate and cold climates as the necessary windproof outer shell. It may be worn over a shirt, sweater and pile jacket, or any combination of the three.
Military specification MIL-C-1911 initially covered a cap made from olive drab shade 7 cotton poplin with flannel lined earlap.
Military specification MIL-C-1913 covers a cotton poplin, field cap with wool pile lined earflaps.