The deck pack comes to you in sizes S and M. The Deck Pack S is best fit for the deck of the Atlantis12, Atlantis14, X-Press and other 24"-30" Deck wide kayak.For the Deck Pack M, it fits the mid-deck of the Tri-Yak and most sit-on-tops over 30" wide, extending storage space while keeping your stuff nice and dry. Of course, the Deck Pack series is also a nice dry backpack even for the non-kayaker!