The classic 135 film format produces a frame that is roughly 36mm wide.
Greek (written with Latin characters / "Greeklish") 36 sirina erasitexniko
If you actually own a device labeled “36 Sirina Erasitexniko,” it likely served one of these roles: The classic 135 film format produces a frame
Ham radio operators (callsigns starting with SV, SW, SZ) used external sirens to signal incoming calls, Morse code practice, or emergency beacons. The “erasitexniko” tag confirms it was not certified for public safety. Morse code practice