VERTECHnk SKY-100 Guitar Sound Hole Digital Hygrometer & Humidifier System Soundhole Cover Dia.100mm for EQ Acoustic Folk Guitars Features: Compatible with 100mm Guitar Sound Hole: Multi-functional digital sound hole humidity controller designed for EQ folk guitars with sound hole of 100mm. Guitar Humidifier Function: Moisten the sponge in humidifier silicon case by water, and install the silicon case to the cover to increase the humidity of your guitar. Guitar Dehumidifier Function: Put the silica gel pack into the small pouch, and fix the pouch to the cover to absorb moisture around your guitar. Digital Hygrometer & Thermometer Function: The sound hole cover is designed with a sensor to monitor the temperature and humidity for outside guitar, and with LCD display showing the accurate temperature and humidity information for you, very convenient e. Normal Sound Hole Cover Function: Can be used as a normal guitar sound hole cover to eliminate unwanted feedback and enhance stage volume. Quick and easy to install & remove, and soft rubber covers the installation edge and ensures no damage to your guitar. Specifications: Compatible Sound Hole Diameter: 100mm Material: Plastic + Rubber Temperature Range: -10.0℃-60.0℃/ 14.0℉-140.0℉ Humidity Range: 20%-95% Sensor Sampling Time: 32s Power Supply: 1 * CR2032 battery(included) Item Size: 11 * 10 * 1.5cm/ 4.3 * 3.9 * 0.6in(100mm); 9 * 8.5 * 1.5cm/ 3.5 * 3.3 * 0.6in(85mm) Item Weight: 66g/ 2.3oz(100mm); 43g/ 1.5oz(85mm) Package Size: 17.5 * 11.5 * 6cm/ 6.9 * 4.5 * 2.4in Package Weight: 250g/ 8.8oz Note: This sound hole cover is not suitable for guitars whose fretboard has reached the sound hole. The guitar showed in the picture is not included. Package List: 1 * Humidity Controller 1 * Humidifier Case 2 * Silicon Gel Packs 1 * Hanger 1 * White Pouch 1 * CR2032 Battery 1 * Black Pouch 1 * Users' Manual(English)