This is an evolved "MK4" flight jacket, the successor to the Royal Air Force (RAF) masterpiece MK3. Size: 7 (Shoulder width 49cm, Body width 63cm, Length 65cm, Sleeve length 65cm) Around 2010, the MK3 was improved and succeeded by the new MK4. The outer shell fabric was changed to 'GORE-TEX'. This dramatically enhanced the waterproof/water-repellent and cold-weather protection, resulting in a significant evolution. The distinctive large collar has a chin strap, which can be fastened to prevent wind from entering. The front has a double closure with a zip and buttons, and the zip area is completely covered with a fly front to completely shut out the wind. The large-capacity "slash zip pockets" located at the abdomen, which are easy to access, also combine practicality and design. The left sleeve is equipped with a padded "utility pocket" (pen holder). The cuffs are adjustable with Velcro adjusters to prevent wind from entering. A "stowable hood" is also installed under the collar on the back, which can completely cover the neck like an anorak. The hood also uses Gore-Tex. A so-called "beaver tail" with Velcro closure is attached to the lower part of the inside of the back. This is used to prevent flapping during parachute descent, and is taken out from the back and passed to the front to be worn. All buttons use "parachute buttons." These buttons were developed by the military so that they would not get caught on parachutes during descent. By not using thread as usual, there is no risk of the thread getting tangled, and ease of removal is also considered. As you can see, this jacket has a high-spec construction that refines practicality. The use of Gore-Tex in the fabric this time has made its functional beauty the highest peak. The sizing is also a short length typical of flight jackets. This is to consider ease of movement so that the hem does not interfere when sitting in the cockpit. This length gives a relaxed body width while skillfully suppressing the clumsiness of military wear. This refined size balance is also one of the reasons why this jacket is popular. It is a very popular and rare model. If you were looking for one, please consider it.