An iconic IWC Mark XI RAF ( Royal Air Force) issued, retains all of its military case-back engravings, 6B/346 1839/48, stainless steel case which measures 36mm. ca with fixed lugs. The dial features the British military broad arrow and the circled ‘T’, indicating that tritium was used for the luminous material. The original dial of the Mark XIs were lumed with radium, but sometime in the early 1960s was replaced by IWC with tritium as it was less radioactive. It fits antimagnetic hands and an antimagnetic cover protecting the manual winding Cal. 89 movement.Mark XIs were produced for BOAC (British Overseas Airline Corporation), the RAF (Royal Air Force), the Royal Australian Air Force as well as other air forces and for civilians as well. The watch is in overall excellent and unrestored condition.