From G7th: 

The Performance 3 is the culmination of years of designing, tweaking, and improving - but most importantly, listening to guitarists and their views on what a capo SHOULD do. Now, coupling our Unique Tension Control system with the revolutionary ART string pad mechanism gives a near-perfect capo experience.

Adaptive Radius Technology:
The ART system within the top bar of G7th Performance 3 capos adapts to the true curvature over your strings and fretboard, exerting completely even pressure across all the strings - setting a new standard of in-tune, buzz-free use. It gives you the maximum tuning stability with the minimum possible tension in EVERY position, on ANY guitar neck. 

Unique Tension Control:
By simply squeezing to attach and squeezing to release, the Performance 3 capo gives you complete and intuitive control over the pressure you place on your strings. Whether it's an acoustic or an electric, you can have confidence that you are in control and will keep your guitar in tune.

Easy to use:
Designed for one-handed use, in any sized hands. With a little practice it's nearly as quick to move between frets as a spring capo, but without the need for frequent retuning.

Versatile:
Stores easily behind the nut for quick and easy access, or on the headstock. Perfect for any steel six-string acoustic, electric or hybrid nylon string guitars.