The Marine Corps’ M1953 lower torso armor was standardized on 18th June 1953 after successful testing by the 1st Marine Division in Korea.1 It was designed to be worn with the USMC M1952 flak vest, or its M1955 successor, and was fabricated from ballistic nylon, weighed approximately 3lbs and featured a side zipper fastener. Commonly referred to as 'Flak Diapers', the shorts were rarely worn in the field in Vietnam, but Marine Corps air-crewmen would often sit on a pair to protect against ground fire.
1. Development of our body armor by Lynn Montross. (Marine Corps Gazette June 1955)