The squeals of feedback WILL ruin your show if you don't find a way to get them under control. That's where the Acoustic Feedback Buster comes in. It plugs right into your sound hole so your acoustic guitar's internal microphone isn't picking up your stage monitor feed and starting that nasty feedback loop. The Acoustic Feedback Buster fits into just about every acoustic guitar -if yours has a soundhole from 3 7/8"-4" in diameter, you'll be good to go.