Ernie Ball Axis Dual Radius Capo Silver. The Ernie Ball Axis Capo’s ergonomic features allow for fast and accurate single-handed key changes. Compatible with most electric and acoustic guitars, the Axis capo offers eight color finishes to match, with a dual-radius design that fits both flat and curved fretboards. Shift capo position single-handedly, and rely on buzz-free clamping pressure that lets your songs sing out in every key. Take the Axis Capo on the road and trust precision-molded rubber pads to protect your guitar finish. On the stage or in your writing space, it has to be the Axis Capo.