Perfect Folk Acoustic Electric Guitar Trigger Quick Change Capo . Guitar Capos are a wonderful and practical thing for any guitar player to own. If you play an acoustic steel string guitar or an electric guitar the Capo is a must have for you. The capo is most commonly used to raise the pitch of a fretted instrument so that a player can perform a piece in a certain key using different fingerings then what they would use if played "open" (i.e. without a capo). In effect, a capo uses a fret of an instrument to create a new nut at a higher note than the instrument's actual nut. Using a capo can bring your guitar playing to a whole new level of creativity. Every guitarist should keep a Capo and a backup Capo in their guitar case.