A manual alarm device including a housing and a displacement element mounted in the housing is provided. The displacement element is moveable between a first position and a second position. Only application of a stable force to the displacement element is configured to move the displaceable element between the first position and the second position.

A push-button (100) includes a plunger sub-assembly (10) that comprises a translation-to-rotation converting part (5), a latch part (6) and a latch spring element (56). The latch spring element connects the latch part to the translation-to-rotation converting part so that rotation of the translation-to-rotation converting part caused by a user pressing the push-button drives the latch part into a position where said latch part abuts a relief portion in the internal surface of a casing (30) of the push-button. Such arrangement of the plunger sub-assembly avoids that numerous repeated locking operations damage to the latch part and/or relief portion. Lifetime of the push-button is thus increased.