For what it is, it's pretty good. I like the metal case, the ground wire. Decent build quality inside. The description is not very detailed - but it does mention the gas tubes. (update: The description now includes _much_ more information!) It does not mention there are no diodes. But it is quite a bit less money than a L-Com with diodes and gas tubes, so if you feel your situation doesn't warrant the additional money for the two-layer protection - then this could be just what you need.
I've been buying much more expensive units that, for some reason, have become hard to get. This one looks to be a good replacement. I do wish the ground-wire was both a thicker wire and at least three times longer - or just replace the wire with a grounding screw and let the end-user attach an appropriate ground-wire. Otherwise - this is a great little unit.
I have not tried to install the devices yet, as I do not have the other parts of my outdoor surveillance system purchased. They look very well made, however, and I expect them to work as I expect them to.