The standard flying helmet issued to RAF pilots and aircrew during the years 1936 to 1941 was the Type B, shown here. The classic design of the dark brown leather helmet with its protruding zippered ear cups became synonymous with the Battle of Britain pilots. The helmet was most often worn with the Mark IIIa goggles and the Type D oxygen mask and was equipped with a leather chinstrap and a friction-type Bennett buckle. The back of the helmet also had adjustable leather straps and buckles to tighten the fit. The Type B helmet was manufactured in four different sizes and was not factory-wired for communications equipment. Communications receivers were inserted inside the zippered earpieces that were separately applied to the helmet for a custom fit. The earpieces were insulated with chamois pads and rubber cups to reduce outside noise interference. The Type D oxygen mask was attached using the snap fasteners arrayed on each side of the helmet. Although designed for use with the Type D mask, helmets were modified at later stages in the war to allow their use with other oxygen mask variations.