Product review (3 stars): Not properly adjustable, despite claims to contrary
I am disappointed to find that the calibration on this product is ineffective. The "pot" (potentiometer) for humidity adjustment can be continuously turned either clockwise or counter-clockwise. There are no stops in either direction. With each full turn, a very quiet click is heard, which is also worrisome. So it is impossible to tell when it is maximally or minimally adjusted.

I used a calibration kit (http://www.amazon.com/gp/product/B000A3UBLA/ref=oss_product) to test this item. Half-turns of the pot, and adjustment periods of 12 hours after each half-turn, produced readings of between 71% and 73%. I could never get it to read 75.5%, as it should have.

Granted, the calibration kit made testing the item difficult. The plastic bag in which it comes is too small to hold the entire item. So I put the probe into the bag, sealed it as well as I could, and then put the item plus the kit's plastic bag all into another, larger plastic bag and sealed that completely. I allowed longer adjustment periods because of this departure from the recommended procedure. (I feel the adjustment periods suggested by the calibration kit -- 24-26 hours -- are unnecessarily long, given how quickly this monitor responds to change.)

Extech makes its own calibrators, which don't require these machinations, but they are absurdly expensive. The use of another maker's calibration kit may throw off readings, but it doesn't change the fact that this monitor cannot be reliably adjusted.

The manufacturer's technical service person was not helpful. He acknowledged that the pot has no stops but insisted it is effective anyway. That is not my finding. I am keeping the item but using it with the knowledge that it is 2-3 percentage points low, at least in the low-70s range.

If anyone knows of a monitor that is *accurate,* I would appreciate hearing about it. (Any response to this posting will trigger an alert to me.)

Also, not that it matters, the unit I received is black and silver, with no green pieces as illustrated on this page.