The simple answer is that if it's small enough to fit into a single rack space it's too small to offer much more protection than is provided by a $15.00 Corcom twin-T filter, and at best that's probably what's in there, if not just a few 50 cent capacitors and three $1 MOVs. That's assuming you're trying to power an amp with it, and not just a rack of processors. Heavy duty filtering and regulation with enough current capacity to handle an amp is going to occupy at least two rack spaces, while the real deal, a transformer balanced A/C supply, will take at least three spaces, and cost at least five hundred bucks.
What I love is the 'conditioners' that have a dozen or more LEDs to tell you that the supply voltage is AFU but don't have the ability to do anything about it. What's the point? Looks pretty, though.