The softly worked up inner lining consists of NYLON and isn´t lined with cotton wool but with a special kind of synthetic downy feather
-a heat insulating hollow fibre.

To avoid the capillaries effects the hollow fibre is worked up with silicone.

Additionally the lining isn´t simply put in but solidly sewn up (water-repellent but still washable).

Zipper in XL-size & with right running closure 
-often an attribute for "made in/for USA".

The knitted waistbands are worked up doubly with sturdy and steady elastic fibre.
The two inner & outer pockets (which can be shut) as well as an arm office complete the classic jacket.

The first nylon flight jacket was called B-15 and was designed in 1944, during the WWII.

The MA-1 was approximated to the B-15, but manufactured without a collar.

Between 1949 and 1950 the MA-1 was issued to the AIR-FORCE  pilots, the NAVY pilots and the flight crews.

Today, the government orders CWU 45/P (Nomex) jackets for pilots and flight crews only.

Nowadays MA-1 jackets are issued for the use of ground crew personnel only, such as security police, base maintenance and line repair personnel.