Excellent condition 1960's Gruen Airflight which features a very cool, complicated jump hour mechanism. The Gruen "Airflight" was designed for pilots that needed a 24 hour reference for flight time. When the hands reach noon all the numerals jump to a 24 hour format and then jump back again to a 12 hour format at midnight. This is accomplished by a rotating dial underneath the main dial. The numbers appear in diamond shaped windows on this neat, and rare, original dial and the minutes are chronicled by a very fine segmented outer track that the sweep second hand hovers above. The seventeen jewel movement is in excellent condition and is winding, setting, and keeping time to about +13 sec/day. As you can see in the video, the jump hour mechanism operates precisely as it should, within a few minutes after noon/midnight. It measures 35MM wide by 42MM lug to lug. Comes on a high quality calfskin strap in very good condition. TZ 92% Here's a video that shows the hour jump function - https://youtu.be/ln1dSVdDGFwPrice is $750 OBRO shipped CONUS, elsewhere at maybe a bit more. Please contact me at sinn_142@ h0tmail.com with any questions.