[Hallicrafters] WHAT IS IT?

[Magoo]

In a box of old Hallicrafters stuff I discovered several
1 khz calibration crystals in octal metal cases and another item, which is
also in an octal metal socket but much lighter and bearing the stamp 23-55-A
and 140-6237.

While the crystals are marked with manufacturer and frequency, this unit has
only the markings above. Several of the pins appear to be jumpered...no sign
of junctions.

Anyone help?

Bill