I bought it because I like Bakelite items.
It's a 1940, portable(?) resistance tester made by Evershed & Vignoles (who still make resistance testers I believe). It's their 500v "Megger" type. Stands 6" by 4" by 2". Bare wires clip instantly into the two holes on either side; the generator handle folds over; you connect a resistor across the two wires and turn the handle. No matter how fast or slow you crank the handle the resistor (if it's not leaking) shows a solid steady reading which is, of course, handy when checking if a resistor has failed but also useful to determine the rating of a resistor that you can't read. Modern versions are, I suspect, smaller but doubt they work any better, look as good or are as much fun to use.