The EXFIL-105 is a massive bag meant to go across a large luggage rack or across the rear of a seat and over saddle bags. It can be attached with any straps given it's many integrated tie-down points. The center section is thermally welded so it is 100% waterproof. The pockets on either end can be accessed without unstrapping the bag from the bike and offer tons of extra, more readily-available storage.