Batboard

I picked a couple of these up thinking they might be cute little bandpass filters, but they appear to have no attenuation at all from VHF up through 900 MHz. Google returns nothing at all on the part number, and Andrew's on-line documentation is pretty useless. They almost look like lightning arrestors in construction. Anyway, if it helps, I'm pretty sure they came out of hybrid power combiner networks.

It's a harmonic filter.

Cool, thanks. Useless for my purposes but luckily cheap (a whole $2 apiece.)

Yep, definitely a harmonic filter. Most likely from a related isolator setup. Nice filters if you need 800 meg stuff. Nice parts to change as you want, too!

I was gonna say a z-matcher. Looks like the piston caps can be reused.