Product review (5 stars): Your Smart Phone can get even Smarter!
This is pretty cool. It turns my iPhone 6+ into a scientific instrument with the free app.

My phone is in an Otter Box waterproof case, so I had to use this with the adapter cable for the headphone port, but it worked fine once I got everything seated firmly. The app lets you take readings of temperature and humidity, log them with a photo of the place being tested along with the geographic coordinates, date, and time, and a bit more. I'm still figuring it all out, but so far it works as advertised. I don't really have a serious need for this kind of information, but I can see the potential. I plan to show it to the guy in charge of safety in my work place; we have incubators, cold rooms, lab instruments, etc. and being able to document the environmental conditions around the building is of real interest.

If I were in the insurance business, evaluating flood damage or inspecting buildings, I can see where this would be really useful. You could measure exactly how damp a basement was, for example. Or, you can use it for your own weather monitoring. If you're a pilot, knowing the temperature and dew point where you are is important for planning a flight. This is roughly the size and weight of a thumb drive memory stick, so packing it in a flight bag would be simple enough. I don't know if it would work with an iPad - it would be worth downloading the free app to see if that runs, and play with the simulation mode before buying the unit. If you're already doing flight planning and keeping nav charts on an iPad, adding this makes sense.

It's ingenious how Extech has managed to make use of the computing power in a smart phone and its existing hardware to add new capabilities with a well designed sensor package. Plug and play - it uses the phone's own power to work, so you don't need to worry about batteries or power adapters. If this keeps up, pretty soon we should see add-ons that will turn smart phones into the equivalent of a Star Trek Tri-corder. This looks like the first iteration of the software app, which is a little rough but usable. It should only improve with customer feedback and field experience.