Another "What is this" thread

I found a couple of them this morning. Someone had thrown them out. It plugs into a standard UK 3-pin socket but the earth pin is a dummy. There's a gap for an external fuse (3 amp according to what's written on the plug). On the front there's what looks like an LED indicator and, rising above it, a vertical perspex panel with an incised design on it like a sunburst: radiating lines of different lengths ending in little balls.

Unfortunately I couldn't find a 3-amp fuse to put into it so I couldn't test it out.