I give up...
Gravy jug
I bought this about 18 months ago. It was only today that I discovered that if you put batteries in it, it lights up!
Doh!
I use them all the time. The rear side of racks full of computers often are dark and have hundreds of various cables and wiring running about like a rat's nest.
Alson much of the newer wiring, such as fibre, is very small.