feedback and enhance stage volume. Quick and easy to install & remove. Soft flexible rubber cover, safe for the guitar finish. The Screeching Halt cover works with most pickup systems without disrupting placement or performance. Suitable for 38 inch/39 inch EQ Acoustic Guitar. Note: Please check the size of your guitar's sound hole to see if this sound hole cover is fit for it. Color: Black Material: Soft Rubber Top diameter: 9.1cm / 3.6in Bottom diameter: 8.3cm / 3.3in Height: 1cm / 0.4in Weight: 111g / 3.9oz Package Including: 3 x Sound Hole cover 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.