Read the Review via the Bike Hermit's blog post
Of all the mechanical problems that can plague the bike traveler, a broken spoke is among the most frustrating. Spoke replacement is tedious and challenging, requires specialty tools and is not a process you want to undertake on the side of the road.
The Fiber-Fix spoke removes some of the hassle from this situation. The super-strong Kevlar cord can be threaded through the spoke hole in your hub flange without removing your gear cluster. Just thread the included attachment into the remaining spoke nipple in your rim, thread the cord down to the hub, back to the nipple and tighten. No need to carry replacement spokes, cassette/freewheel tools, etc.
Detailed instructions and a spoke wrench are included.