The Planet Waves Humidity Control Kit for Acoustic Guitar, is a complete humidification system for acoustic guitars. Included in this kit are the humidifier, and the precision designed digital hygrometer which indicates accurate relative humidity levels ranging from low (under 20%) to 99%. The temperature can also be displayed in Fahrenheit or Centigrade ranging from -32f to 122f. The HTS (Humidity Temperature Sensor) includes a programmable set point, as well a memory feature, that indicates date/time of the highest & lowest temperature/humidity levels that the instument has been exposed to. Be sure to purchase one for each of your fine acoustic instuments. It's a wise investment!