When the only way you know how to play “Amazing Grace” is in G, and your singer can only sing it in C, a capo will save your performance. In fact, with a good capo you can play everything in G-based chords even when the rest of the band and singers are performing in their chosen key. All you need to do is move the capo up or down the guitar’s neck to match. This is the guitarist’s best-kept secret! Here’s how to find a capo for your needs.