Humidity guage for your fine string instrument.
This Stretto Digital Hygrometer will let you know to a certainty that your instrument is at the proper humidity. The thermometer will let you know that it is at the proper temperature. They will also let you know when your bag needs to be replaced. Your humidifier keeps an eye on your instrument, but who keeps an eye on your humidifier? The Stretto Digital Hygrometer, that's who.