noun
flip clock; flap clock
A clock that displays the time using split flaps that flip over, often with a distinctive flapping sound.
駅の待合室にパタパタ時計が置いてある。
There is a flip clock in the station waiting room.
パタパタ時計の数字が変わる音が好きだ。
I like the sound of the flip clock's numbers changing.