Type B-10 "ROUGH WEAR CLOTHING CO. The Type B-10 is a fabric flight jacket for use in moderate temperatures (+10°C to -10°C), adopted by the U.S. Army Air Corps in July 1943 as an alternative to leather flight jackets. During World War II, the U.S. Army, suffering from a sudden shortage of leather, reviewed the sewing aspect and productivity, and developed a flight jacket made of cotton twill, which could be mass-produced. The lining was made of alpaca duck hair wool pile, which was less bulky than sheepskin and had the advantage of being lightweight and having high warmth retention. The "AN" series, such as the AN6552 and AN-J-3A, was developed for common use by the U.S. Army and U.S. Navy, but the Army Air Corps never fully adopted it, so the B-10, a new type of cloth jacket, was made from this type.