It makes the chain too tight, not enough slack on my Xtrainer. I used the tool for a couple years, and I kept getting countershaft seal leaks like crazy. I also went through three expensive O-Ring chains and 4 front sprockets.
After a lot of online sleuthing, it became apparent the chain adjuster tool is no good, I start allowing for nearly 50mm of chain slack above the swing arm at the middle of the chain when on a stand. Never had another leak or ruined chain in over three years now.
For owners who think they want this, go read some forums from owners thoughts. It's very easy to get chain slack right without this tool.