Ortega Guitars HUMIBUSTER80 Feedback Buster and Humidifying System for Acoustic Guitar Soundholes, 85mm Humidity Control + Feedback Buster, classic soundhole, 85mm All in one Feedback buster & and humidifying system 85 mm diameter, fits most acoustic guitars soundhole Equipped with sponge and pores to maintain a relative humidity for your instrument and protects the wood from drying out in dry conditions Eliminates feedback for live performances Quick and easy to install & remove <a href="https://www.amazon.com/b?node=14770868011"> International products </a> have <a href="https://www.amazon.com/gp/help/customer/display.html/ref=nav_cs_help?ie=UTF8&nodeId=202045290"> separate terms, </a> are sold from abroad and may differ from local products, including fit, age ratings, and language of product, labeling or instructions. Manufacturer warranty may not apply <a href="https://www.amazon.com/b?node=14770868011">Learn more</a> about Amazon Global Store.