Accuracy
How many seconds a day your watch gains or loses, heard through your phone’s microphone.
Zelos · Swordfish V2 300m Diver Seiko NH35 Helical Blue
ChangeSwordfish V2 300m Diver Seiko NH35 Helical Blue
Somewhere quiet, lay the watch caseback up on something soft. Rest the bottom edge of your phone on the caseback and keep both still.