Background item: The same item… recently repurposed… as a "radio detonator unit." The slide-switch (which formally controlled a flashlight function) "arms" the device (sliding the switch downward reveals a flashing LED indicator). Pressing the adjacent pushbutton, causes the LED to stop flashing, and increase in brightness… ostensively transmitting the detonation signal.
This kind of repurposing is fairly common plaice in prop building… especially if your client is on a tight schedule and/or budget. We always like to hang on to nondescript objects like the SONICGUARD, because of their utility. Having interesting objects on hand that posses useful attributes (working switches, LEDs, battery chambers, etc.) can same valuable build time… and keep costs down.