Product review (1 stars): Great idea.
Great idea .. too bad device is grossly inaccurate.  Device reports 51% RH (which would be perfect) . place 2 other hygrometers on either side and both were 40%.  For $50 this is a rip off .. I would suggest putting an Oasis digital hygrometer (or similar, Oasis was pretty accurate +-1%). Love the D'Addario humidification system though .. works great.  Just monitor your humidity with a reliable hygrometer.