This Planet Waves O-Port is proven to enhance the sound of any acoustic guitar and kill feedback without the use of electronics. It’s has been tested under the scrutiny of world-renowned acoustic engineers and sound producers to improve tonal quality. The result is a fuller, richer sound with noticeably increased sustain and harmonic range. The tonal enhancement provided by the Planet Waves O-Port is particularly pronounced when the acoustic guitar is plugged in and amplified, resulting in a much fuller sound, a stronger signal to the internal pickup, and significant feedback control. The Planet Waves O-Port fits in most acoustic guitars with a round soundhole, regardless of make or model.