Sound Hole cover - TOOGOO(R) Acoustic Guitar Sound Hole Cover Block Plug Screeching Halt for 40"/41" EQ Black Eliminate 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 40"/41" EQ Acoustic Guitar.