Many devices can be used to mark passage of time without respect to reference time (time of day, minutes, etc.) and can be useful for measuring duration or intervals. Examples of such duration timers are candle clocks, incense clocks and the hourglass. Both the candle clock and the incense clock work on the same principle wherein the consumption of resources is more or less constant allowing reasonably precise and repeatable estimates of time passages. In the hourglass, fine sand pouring through a tiny hole at a constant rate indicates an arbitrary, predetermined, passage of time. The resource is not consumed but re-used.
Reminisce fond memories of your school years with this 8.3" Retro Modern Wall Clock. Fashioned with contemporary and retro accents, the wall clock will transport you to your childhood days with its vintage design. Indulge in nostalgia with this simple and elegant wall clock. Crafted out of ABS thermoplastic and glass components, the wall clock is will elevate the vintage style of your home. The top and base materials are made out of sturdy ABS thermoplastic which gently wraps itself around the...
This Technology Curved Tabletop Clock and weather instrument offers curve-appeal. It also offers dynamic white LED display with a mirrored lens which can be seen from across the room and in darkened rooms. Features dual alarms with adjustable settings: HI/LO sound volume, programmable alarm days, snooze duration (5-60 mins), and auto-dim. Displays your current indoor temperature (F only) and humidity and can charge a mobile device with a bonus USB port in the back of the clock. Table standing...
This selection offers an analog display with hands and a built-in digital wall clock. Metallic gray wall clock with a flat bezel framing the dial. White dial with large black Arabic numerals, black hour, minute and second hands beneath a glass crystal. LCD calendar in the dial displays the month, date, and day of the week. Quartz, battery operated movement.

Alarm clocks, like almost all other consumer goods in the United States, ceased production in the spring of 1942, as the factories which made them were converted over to war work during World War II, but they were one of the first consumer items to resume manufacture for civilian use, in November 1944.[13][14] By that time, a critical shortage of alarm clocks had developed due to older clocks wearing out or breaking down. Workers were late for, or missed completely, their scheduled shifts in jobs critical to the war effort.[14] In a pooling arrangement overseen by the Office of Price Administration, several clock companies were allowed to start producing new clocks, some of which were continuations of pre-war designs, and some of which were new designs, thus becoming among the first "postwar" consumer goods to be made, before the war had even ended.[15][16] The price of these "emergency" clocks was, however, still strictly regulated by the Office of Price Administration.[14]

“I am the heaviest sleeper and was setting four or five alarms on my phone to wake me up. After being late a few times, I decided to purchase this alarm clock to help me wake up on time. I couldn’t be happier with my purchase. … The bed shaker is super important. I put it under my pillow, and it shook me awake; the loud beep helped too. If you can sleep through earthquakes and shouting family members, this is the alarm clock for you.”