101-103mm sound hole diameter.
Used as a guitar humidifier, simply moisten the included sponge and install for reusable humidification.
Working as a guitar dehumidifier, using the included desiccant to absorb moisture around your guitar.
Can also be used as a normal sound hole cover to eliminate unwanted feedback.
Soft rubber covers the insert edge, no damage to your guitar.   

Specifications:
Material: Plastic + Rubber
Compatible Sound Hole Size: Dia 101-103mm
Item Size: 11 * 1cm / 4.3 * 0.4oz
Item Weight: 53g / 1.9oz
Package Size: 14 * 12 * 3cm / 5.5 * 4.7 * 1.2in
Package Weight: 102g / 3.6oz

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 * Sound Hole Cover
1 * Sponge
1 * Bag of Desiccant