The Spoc is a really compact little motion-capture device, (meaning, simply, the rope slides through it in one direction and locks when weighted). It’s beautifully made, fits well in the hand despite its small size, slides effortlessly on the rope and grips reassuringly on lines from seven to 11mm (including Edelrid’s 6.5mm Rap Line II).
A cool addition to the Spoc is a carabiner hole big enough to pass the gate of a locking carabiner through, so that you can change the orientation of the biner without taking the Spoc off the rope.
The secret of the Spoc’s performance is a high-efficiency, small aluminum ball bearing wheel and a diminutive, but aggressively toothed cam that gives extra grip on icy or dirty ropes. The cam is retracted with a small wire with a rubber finger grip.
If you are using the Spoc just for motion-capture, (say, as part of a solo top-roping system), this may seem like an unnecessary and fiddly addition. It’s there, however, for an especially cool function that will appeal to big wall climbers and new routers and come in useful in rescue applications.
The wire backstop allows the cam to be fixed in a released position, so that the efficient pulley can be used without the cam, which can nonetheless be engaged whenever needed. Highly recommended for big wall and aid climbing, glacier-travel and any rope ascending functions. (Edelrid Spoc, 60 grams, MSRP: $121)