Hygrometer/ humidity levels

hey all,
i dont want a big show pc.
and i dont want to spend a lot, but I want to occasionally know if its too dry or humid in the HOUSE.
I see nice, very small Hygrometers like 2.75" but they list for Cigar/ or Guitar....
http://cgi.ebay.com/2-75-Hygrometer-for-Humidor-Acoustic-Guitar-Violin_W0QQitemZ290290342034QQcmdZViewItemQQptZWeather_Devices?hash=item290290342034&_trksid=p3286.c0.m14&_trkparms=72:1205|66:2|65:12|39:1|240:1318|301:0|293:1|294:50

Is there any reason I cant hang this in the house?

that's my feeling, been searching online... dont see whynot, although i have read the analog need calabration.... digital do not.
thanks for the reply.

thanks man, i was reading how to calibrate them.. with salt and a baggie.
cool stuff.
think i'll order it.