The instruction manual states:
"The Federal Jr. is a sturdy instrument, well designed and built in every detail. There is nothing in it that will wear out and no replacements will ever be required. It should, however, be protected from moisture, excessive temperature and from very severe mechanical shocks. If given the care due, such an Instrument will serve as a source of education and amusement indefinitely."
Well, after a 101 years, it seems to be going strong, though I would not say it was the most sensitive radio ever made. Even with a 1N34 diode substituting for the crystal, it was not the greatest crystal radio I have ever used. Still it is a beautifully looking device.