Non-tactile membrane switches come in useful mostly when tactile feedback is not needed (e.g. when the device displays a relevant character, lights up a LED, or starts an expected operation after the key is depressed).
Principle of a non-tactile membrane switch:
The main advantage is a very favourable price and a very slim design.
The type nomenclature of non-tactile membrane switches in TT Klavesnice is TS 523 0 xxx
TT Klávesnice, a.s., Hruškové Dvory 56, 586 01 Jihlava, CZ