Old monitors with protective film.
By the way, I remember working in the printing, there was a similar protective screen on the monitor. And whether the grounding wire was rubbed, whether the computer was in the outlet without grounding, or what other problem, but this screen accumulated static voltage in unusual volumes. And everyone who wanted to tap the screen with the finger "but this logo we will move here on the form" received a long, about a centimeter, bright blue spark. That literally in a couple of techniques clearly knocked off the habit of strangers ticking their fingers where they do not need to. I’m missing such a Devil now.