This is a special tool that fits all bevel drive Ducati twins, used to tighten or loosen the clutch cable adjuster locknut against the engine. A standard open end wrench is too thick to fit in the minimal space and locking it down once you have it adjusted is critical.
The tool slips over the cable so you can easily lock or unlock that nut. Use this tool on the locknut and use your own standard 10mm wrench on the adjuster. Easy-peazy.
NEW: We now make these using a 4.25" long combo wrench so it easily fits between the locknut on the cable adjuster and your carb.