Copal was a Japanese manufacturer that specialized in flip clocks in the 1960s and 1970s, most of them with a mains synchronous motor. Some are sold with the brand name Caslon.

Several models are of interest to this website as they are battery driven and have a tuning fork movement and so hum rather than tick.

The model shown is the T5, first of this type. It was available in yellow, red, orange, white and green.

The T7 has a sllightly more modern looking design in a more rectangular case and has an alarm.

The T11 is a horizontal cylinder shape, made of metal unlike the plastic T5 and T7 and has an alarm set by rotating the left hand end of the casing. 

All run on a single D cell and are not self starting. There is a lever to flip or a chain to pull to start the clock and a window allowing the flywheel rotor to be seen turning.