The Rock Exotica Solo Aid ($80) is a mechanical self-belay device that uses a cam to cinch the rope and catch you in a fall. The Solo Aid has a breaking strength of around 6000 pounds (each unit is tested to 2000 pounds at the factory), won’t harm or come off the rope, and self-locks.

The Solo Aid is about 2/3 the size of a Jumar ascender, weighs six ounces, works on 10- to11-millimeter ropes, and consists of a frame, cam and safety. The unit is taken apart and reassembled around the rope (a procedure requiring some practice); a locking carabiner clips through the frame to pin the safety in place. The individual parts are joined by perlon cord to prevent dropping them, and cryptic assembly and rope-travel directions are etched on the frame in case you forget how the device works.

The Solo Aid ties to your harness with a short loop of eight-or nine-millimeter rope. To keep the device out of your way and oriented in the proper position, Rock Exotica recommends attaching the Solo Aid to both a sit and chest harness. We used the unit without a chest harness and found that it worked fine as long as the unit was set up properly (we mistakenly put the rope in backwards several times while practicing on the ground).

The Solo Aid locks itself on the rope and lets slack out easily and smoothly when you lift the cam. But giving yourself rope with the Solo Aid still takes one hand, impeding its use for free climbing.

We preferred the Solo Aid over the clove-hitch and figure-8 methods detailed above for free and aid soloing. The device is faster and easier to use than any knot system. Furthermore, the Solo Aid works well for rappelling, and can be used, although with some difficulty, for a toprope self-belay. For serious or frequent aid soloing, the Solo Aid is worth its weight in copperheads.