Accuracy
How many seconds a day your watch gains or loses, heard through your phone’s microphone.
Zelos · Swordfish Bronze 300m Diver ETA 2892 Black Sand
ChangeSwordfish Bronze 300m Diver ETA 2892 'Black Sand'
Somewhere quiet, lay the watch caseback up on something soft. Rest the bottom edge of your phone on the caseback and keep both still.