As with the other devices, not enough information. Photo of the devices, where it was found, what you think it is supposed to do, what it does instead, what voltages it appears to use, what frequencies are present in surrounding circuit, how many legs it has, and whatever else you know or suspect.
DuoFone is a former Radio Shack product. You might try your local Source at Circuit City location ( in Canada) for a datasheet, or Google the part number for more results.