[hedora]

Unlabeled slider switches were never particularly common.

For instance, my old stereo has push button toggles, where “in” means “on” (this convention was common because of how those switches work), and three way levers with labels on two of the three positions (there’s no space to label the middle position, and it means “default”.

[exiguus]

I remember them on mp3-Player, Walkmans, Microphones and even Mobile-Phones. Usually on device that you want to lock or particularly turn on and off. And sometimes you have to push them hard with the help of your Fingernail.