Perpetual calendar
Calendar that automatically accounts for the different lengths of the months as well as the leap years of the Gregorian calendar.

Power reserve display
Function in mechanical clocks and watches that indicates how much energy (torque) is left in the mainspring.

PVD coating
Physical Vapor Deposition, a process in which pure metals are deposited onto watch cases in a vacuum. PVD-coated cases are especially scratchresistant, gentle on the skin, and non-allergenic.

Quartz movement
A timing mechanism that sends an electric current from a battery or solar cell to a synthetic quartz crystal. The resulting oscillation drives the movement. (The deviation is about one second per week.)

Radio-controlled clock or watch
A clock or watch in which the time displayed is controlled via radio technology, with the time coming from a central time signal transmitter. Constant synchronization makes the radio-controlled timepiece the most precise way to measure time. As an added convenience, the time displayed automatically adjusts for daylight saving time.

Radio-controlled solar clock or watch
A radio-controlled clock or watch that is driven by solar power. The solar power is stored in a solar cell on the dial and supplies sufficient energy to run the timepiece so that no battery change is needed, even in low-light conditions.