Chronograph 7413-6

A steel Longines chronographChronographA watch function for starting, stopping and resetting an elapsed-time measurement independently of the ordinary time display. with a screw back stamped 7413 6 and manually wound calibreCaliberThe designation of a watch movement, identifying its design or movement family. 30CH. The documented example has blue tachymeterTachymeterA chronograph scale that converts the time taken to travel a known distance into average speed. The distance and scale units must correspond. and red telemeterTelemeterA scale estimating distance from the interval between seeing an event and hearing its sound, such as lightning followed by thunder. scales; the suffix alone does not authenticate a dial configuration.