Shubb Capos are by far the best for not creating tuning problems. Learn more...
About the MODEL

For your nylon string guitar,
the capos on this page are the right choice. The C2, C2b, C2k, and
C2a are the same size, shape, and material (brass) and differ only in appearance. The L2 (Lite) is made of aluminum, and weighs half as much. The S2 (deluxe) is made of stainless steel and features a roller
design. It also has additional benefits due to its geometry (learn
more...)
fretboard radius
Almost every nylon or gut string guitar has a flat fretboard.
On those rare instruments that might have a radiused fretboard,
then either our model 1 or model 3 would be the right choice.
Conversely, it is very unusual to find a steel string guitar
with a truly flat fretboard, but in those rare cases -- perhaps
custom instruments -- then our model 2 would be the right choice.