The Shure 520DX is a legendary microphone manufactured by the Shure Brothers. It's also known as the 'Green Bullet'. Almost any older/blues recording that uses a harmonica used a Green Bullet to capture the sound. Blues harp legends that used the 520DX range from Little Walter and Sonny Boy to Chicago harpman Elwood Blues (aka Dan Aykroid) from the Blues Brothers. The mike is small and bullet-shaped, about palm sized, with a built-in cord.