small fedtro vacuum tube tester

This tiny vacuum tube tester weighs about 1 pound. It has two leads coming out of it orange and black, only one of which is terminated in a pin. There seem to be spaces for 7 pin and nine pin tubes in addition to octal and locked all tubes. There is a neon indicator lamp as well. It looks like 120 volts is provided via of a double male plug that is UL listed at the side. However I do not have a cord, and this tester is untested. The two sides are secured with pins rather than screws and so I am unable to easily remove the back cover. However I took a picture that indicates the parts that are on the inside. There does not seem to be a Transformer so this tester cannot provide the heater voltage for the tubes that you might want to test with it. However, it can check for continuity in the heater. Heaters burning out is a common failure mode for tubes, so this would be a useful first check if your tube is not working.