This damper rod holder is equivalent to the Yamaha special tool part number YM-1300-1 or 90890-01462.
It works on the 2001 Yamaha V Star 1100 Classic forks. It will work with many of the forks of similar design that were built by KYB for various motorcycle manufactures. I use it with a Craftsman 20 inch long, 3/8 drive extension, which is just about the perfect length. You can pick one of those up at most Sears stores for about $15.
If the top of your damper rod has a round hole, without any tabs for a damper rod holder to engage, this is probably the correct tool.
Just because it's the correct tool, doesn't mean it's easy to use. To hold the damper rod, you're putting a square tapered peg into a round hole and expecting it to hold. Doesn't always work. Sometimes the damper rod will still spin until the tool gouges a ridge into the top of the damper rod that the tool can grip. There have been times where I used this tool and was able to remove the damper rod bolt with ease, using nothing but hand tools. Other times, I've needed to use an impact gun to remove the damper rod bolt.