Board Thread:General Discussion/@comment-93.200.67.104-20140703113811/@comment-25099139-20140703115531

No, it says 100% because, if you have the money for it, you can do box summons until you get the UR, whether that is on your first try or 99th summon, your are guaranteed a UR because there is no way you won't get a UR after 99 tries.