Environmentalists who play the guitar—listen up. The Instrumental Music Center is celebrating Earth Day and National Guitar Month in a way that will help you rock your world. The center will host a guitar recycling and restringing event on Thursday, April 7. All you have to do is bring in old guitar strings, and event sponsor D'Addario's people will restring your instrument—electric or acoustic—with NYXL or nickel bronze acoustic strings for free.