Infinity Ring 7 Book Collection Series

this is a 7-book hardcover set: When best friends Dak and Sera stumble upon the key to time travel-a handheld device known as the Infinity Ring-they're swept up in a centuries-old war for the fate of humankind. Recruited by a secret society named the Historians, the kids learn that history has gone disastrously off course. Now it's up t them and Historian Riq to travel back in time to fix the Great Breaks. Fix the Past, Save the Future