In the early 1930s a specific category of chronograph watches were nicknamed telephone timers. They were designed with special markings that highlighted a range between every 3 minutes on the subdial register. After each 3 minute marker was reached, it would remind the wearer that they would need to insert another coin in the meter to continue their call.
Similar to this method of counting seconds and minutes with a direct correlation to the wearers action - the Metric Chronograph has specific markers that specify when the optimal espresso shot has been extracted. This is the world's first wearable espresso shot timer. The time for this ranges from 25 to 35 seconds - depending on the barista and the machine.