Planet Waves Tri-Action Capo
Planet Waves recently upgraded the Dual-Action Capo to the Tri-Action Capo. The features are identical to the Dual-action, but adds a function that will grasp a flatpick. The capo's compound action requires little force to open the capo and it works easily with one hand.
It is built from very lightweight aluminum, and is designed for radiused fingerboards. It works great on 12-strings as well!