I bought this but I really don't use it. A 9/16 open end wrench really does a better job. This wrench is soft plastic (to keep from marring the rings) and it deformed the first time I used it. I ended up just using my 9/16 wrench. Just be carefull and your 9/16 will work just fine and won't mar the rings.
I was a bit disapointed to find this wrench to be made of plastic. It is heavy plastic, but I still thought it was made of steel, or maybe aluminum. I have used a 9/16" wrench inthe past, and they always worked just fine.