This is the clamp like accessory track contactor that Lionel put out to be activated by the wheels of the passing train.
This one is from the 1950's-60's era of Lionel.
MADE IN THE USA.
The 154C is mostly associated with the 154 Highway Flasher, but it was used to operate other accessories as well. It can be adapted to activate any other accessory that requires the flash like highway flasher. And it is much easier to use this with your Marx highway flasher than to try to hook it up with the method Marx suggests.
CONDITION: C5. As you can see, this one is used with significant wear, some surface rust and oxidation. None of this interferes with its operation. The insulated tape on the upper lip looks good, but when it is older, it flakes, and can always use replacing. We suggest using the brown packing tape or masking tape.
If you need instructions, let us know upon winning--we can supply a copy.