Polerouter 20217/1

Early steel execution bearing the original Polarouter dial spelling, with a black crosshair dial and calibreCaliberThe designation of a watch movement, identifying its design or movement family. 138SS bumper windingBumper automaticAn automatic winding system whose pivoting weight travels through a limited arc, meeting spring buffers at the ends of its swing. Wrist motion moves the weight to wind the mainspring. Unlike a full-rotation rotor, the weight cannot turn continuously through 360 degrees; the travel angle varies by design.. This unprefixed reference is distinct from the later S-prefixed Polerouter series.