The Thalia Capo is unique because you can swap out the fretpads to get a perfect fit on your guitar. For 12-string guitars we recommend the use of our XL High Tension Rubber fretpads, which are 2mm taller than standard fretpads that come with every Thalia Capo. This extra height increases tension to ensure that the octave strings on your guitar are fretted perfectly. The XL High Tension Tuning Kit comes with every capo so you won't need to order this separately. All you need to know is the fretboard radius of your 12-string to get the perfect fit!