Digital hygrometers are much better than cheap analog ones. I got a quality Diamond Crown hygrometer, and for the past 3.5 years it has never been more than 1% off. I check it every 90 days or so by taking it to my cigar shop and asking the owner to put it in the humidor all day. Then we check it, and it has never been more than 1% off the DC hygrometer he has installed in his humidor. So it was well worth the $40 I spent.