Product review (5 stars): So simple and so inexpensive
Step 1: Take pak out of its plastic baggie.
Step 2: Place in humidor.

So simple and pretty accurate. Tested its RH using a digital and an analog hygrometer. The readings wavered between 69% and 71% at times, but they read 69% far more often. I will be buying this product forever or until it is discontinued. I can't comment on how long they actually stay "fresh" since I just bought them about two weeks ago. But I don't foresee having to come back and deduct any stars for that.

Pros:
+Stupidly simple to use
+Dirt cheap

Cons:
-All good things come to an end. (At some point I'm going to have to go in and swap them out)