Is the Roxy "In Between" Duffel bag accepted as a carry on, when flying?

I got a luggage set, its called Roxy In Between Luggage. I was wondering if anyone else had it and used the duffel as a carry on when flying. I would hate to get to the airport and not be able to take it. I looked at the dimensions and the requirements online, but they are worded differently and I am not sure if it is acceptable. I am flying with Frontier Airlines, if that helps. Thanks! :)