After assembling this product i left it on my windowsill below a badly condensated window. After 2 weeks all that had happened was the crystals had got damp and formed a hard clump, there was not a single drop of moisture in the drip tray below.
I was very disappointed. I opened it up to have a look at the crystals and i dryed them with paper towel, then i pushed the hard clump out of the base a little just to try and loosen it a bit.
I then put it back in position and it is now collection a quarter of a pint of water in the tray each week. That might not seem a lot, but i am actually quite impressed considering how little it cost. My window is still really condensated so it didn't really help me with the task i bought it for, but it is at least doing something. It's probably ok for very minor moisture problems, maybe in a small cupboard, but i can't see 1 of these ever being enough to help condensation on windows.