[Milsurplus] Xtal question

[Hue Miller]

I have 3 of those Valpey crystals and also had wondered what
they were. There is a single screw on top the package but 
removing the screw does not seem to allow opening, etc. or
actually accomplish anything that i can detect. I wonder what
that is for. I was hoping i could open the package which is the
round "pill shaped" form similar to 1930s crystals. If i cannot
figure out a way to open the crystal i suppose i will just donate
them to some LF experimenters, the frequency i think doubles
to our 1 watt limit experimental LF band here.

The other crystal, never seen one with 6 legs, but 4495 is a 
classic air-ground frequency of the Army Air Force in WW2.
-Hue