This Jacket is Known as the 'Irvin Jacket’, it takes its name from Leslie Irvin the inventor who designed this in early 1930's. First produced in the Letchworth factory in 1931, the design was officially approved by the Air Ministry. By 1932, the this jacket became standard issue to all RAF pilots. Though originally produced by the Irvin Parachute Co., the demand required the work to be contracted out to a number of manufacturers during WWII. This accounts for some differences in design such as, sheepskins used, and the varying colors as most of the labels were removed. One reason being that the label would have the maker and this would be useful information. Four panels were used due to the shortage of materials during the war period, where nothing was wasted and the later war jackets became multi panel. The FiveStar Leather RAF Flying jacket is pattern from a late 1940/41 original 4 panel jacket, retaining the collar strap. The purpose of the collar strap was designed for open cockpit flying, where the strap was pulled over the head to sit on the forehead to help keep the collar up. It was discontinued on later war jackets. To maintain originality, the FiveStar Leather Irvin has been fitted with reproduction Lightning Zippers, on which the puller has been molded from an original puller to its exact size, and design, We specifically Die Cast its Buckles which are made from Brass Material, We developed a Special Sheepskin Leather for these jackets. Overall FiveStar Leather RAF Flying Jacket have the true to original Jacket Details, we also claim that we made the most affordable RAF Flying Jackets with True and Authentic details today, its hard to find this elsewhere in this Price. Another major advantage of FiveStar RAF Flying Jackets is that we also made your custom sizes on demand, If you don't find your size in our standard size's please send us an email with your custom size details and we will make this according to your sizing requirements.