1977 - It's only 5-3/4" long, tapered prongs 1" long and 1" apart.
The teeter-totter action (*Four seat teeter-totter for Lilliputians)
is less than an inch. The chain latch suggestion seems to be the
best, so for, IMO, but Rob hasn't verified that as correct. There are
old latches, for large shutters, that have a single sided/arm lever
mechanism, but not double pronged. Those shutter latches had 2 parts,
one for the shutter and one on the window facing. I can't think of
any other bifold closure (?) that would require that (1977) sort of
mechanism (with another piece to go with it at each end), either. But
it's obvious there is another part that plugs into or is caught/hooked
onto those prongs. Whatever movement is there, is slight.... to
assist in leveling/aligning 2 sides of something? I can't imagine the
unit standing alone, with some small extensions (plug-ins) on each
end, only, like a door knock missing the knocking parts.
1980 - Whatever it clamps, it can't be too tight. The top knob is
made for hand tightening, at most, not cranking. I highly suspect
it's for domestic use, only... guessing: maybe for holding some sort
of bag/sack for hand sewing closed. *Chicken/turkey/goose guillotine!