The Aero-Compax’s name derives from its use in the aviation world, with tachymeter track for precise timing. The dial features a minute, half hour and hour chronograph timer, this allows pilots to time long journeys or exercises. Additionally to this at 12 o’clock there is a subdial for a second time zone, with full minutes and hour hands to display the time. However, this fourth subdial, featuring hour and minute hands, could also be used to memorize the start of an appointment or operation (by means of an additional crown at 9 o’clock) and therefore was advertised as ‘The businessman chronograph’ when it launched in the 40’s. A rose-gold version like this is very rare, especially in the ‘Jumbo’ size of 37mm!