I'm a fan of Polyphaser and would suggest anyone wanting to learn about lightning protection to read this publication from Polyphaser:
http://members.rennlist.org/warren/LightningProtectionAndGrounding.pdf
I hope there is no copyright infringement from whoever posted it on the Internet since it originally cost about $20.
Anyway, the gas filled protectors work by connecting a little capsule containing a gas across the center conductor and ground of the coax and the gas conducts at a certain predicted voltage. The voltage where the gas ionizes and shorts the center conductor to ground is based on how much RF power the lightning arrestor is rated for so it doesn't conduct during normal operation but it will conduct with higher voltages from a lightning strike. When the high voltage condition (strike) is done the gas tube usually returns to normal or it may be permanently shorted but most models allow you to easily replace the gas tube.
Polyphaser in general does not use gas tubes and one potential problem is the arrestor is at a remote location and the radios will not operate until someone fixes the blown gas cartridge. Most Polyphaser arrestors are designed to take multiple hits and not need replacement except in extreme cases.
prcguy