FREE: Signal splitter

The listing, Signal splitter has ended.

What's this? On some cassette recordings of Books on Tape they would save money by recording on all 4 tracks of a cassette. The recording was mono so one track would be side 1, left channel. The second track would be side 2 left channel. Track 3 was side one right channel and track 4 was side 2 right channel. To listen to the book one would have to either turn down the volume on the 'other' track or use this splitter.
The male end would go into the cassette player and your earphones would plug into the female side, either side marked "L" or the side marked "R". Then the same data from one track of the cassette would play to both earphones. When you've finished side one and side two, you would turn the tape over again and plug your phones into the other outlet.
Since it would be hard to find recorded books cassettes that were recorded in this 4-track manner, perhaps you can find another use for this signal splitter.