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Mk.IV - First issued 1940: The third type of goggles used during the Battle of Britain and specially designed for the type "B" helmet. Black painted brass frames with split glass lenses in hinged housings which open outwards. Leather padding over the nose area. Large sprung cord side loops to fit around the helmet earcups. Leather back strap. Without the detachable polarizing flip shield (it was common practice for pilots to remove this device).