Feature:1. Innovative 2-in-1 design with a precise indicating needle humidiometer, environmental protection, no battery. Real-time, humidification and testing are performed simultaneously.2. Safety, the humidifier eliminate potential problems such as warping, shrinking, worse yet, cracking.3. Portability, easy to install and carry, no need to move strings and it can be taken away in the pocket.4. When the ambient humidity is below 40%, we can fill guitar humidifiers 2 inlets with 5ml water respectively with a refillable bottle then clamp the guitar humidifier on the edge of the sound hole.5. Made of high quality ABS and plastic material, durable and long service life. Including gold detection hygrometer head and black ABS plastic humidifier.Specification:Item Type: Guitar HumidifierMaterial: ABS+PlasticColor: As shown in the pictureProduct Size: Approx.87x54mm / 3.43x2.13inApplicable Musical Instruments: Classical, folk, ukulele, etc..Package List:1 x Guitar Humidifier1 x 100ml Dropping BottleNote:When the ambient humidity is above 70%, please don't use the guitar humidifier.