Solid wood guitars are more sensitive to air humidity.A humidifier can effectively prevent the guitar panel from cracking and maintain good sound quality. Efficient and comprehensive moisturizing, the recommended suitable humidity is 45%-65%. Small size, silent operation, no noise The sponge design guarantees that it 't leak in any way.It is fixed on the strings when in use, it not touch the guitar body and not put any burden on the strings. Colour:A:Silver Material:ABS Package Contents: 10 x Guitar Sound Hole Humidifier Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.