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 MQ-1 (Model Quartermaster 1) olive drab pile field cap is a modified version of the olive drab pile field cap. The pile lining of the original visor, which caused visual interference and forehead discomfort when the visor was lowered, was eliminated. The MQ-1 cap was adopted as the M-1951 pile field cap.
The M-1943 MQ-1 field jacket was a modified version of the M-1943 field jacket that contained inner buttons for attachment of a removable liner. The jacket was adopted as the M-1950 field jacket.