To us, this looks like a trunk. The Sci'Con Elan 615 Roller 2 Saddlebag is the biggest and boxiest Sci'Con bag we sell. It also features the Roller 2 mounting system, a great, simple, clean design that is secure and doesn't abrade your pretty carbon-fiber seatpost.Sci'Con's saddle bags are notable for their retention systems. No Velcro straps. The design has been updated to the new Roller 2 mounting system. If you recall the original Roller System (now Roller 1), you start with a plastic cleat that secures to your seat rails with the twist of a knob. Then you install the bag by matching the cleat with the opening in the binding mount. And give it a 1/4 turn. The Roller 2 takes that same idea and adds two tire levers to the design. There's one mount for a tire lever outside the bag, and a mount for a tire lever inside the bag. To make sure the lever slots work, Sci'Con includes the levers. Building the two levers into the design frees up space in the bag, so you can fit more into it. And you can fit in plenty. With some smart packing (always take the air out of your tubes before rolling them), you can probably fit two tubes, a full-size CO2 inflator, a few spare cartridges, your phone, an energy bar or a few gels, a multi-tool, a patch kit, and possibly a mini-wallet.The bag itself has a mix of materials. The side panels are carbon fiber weave. The main panels are Cordura. Reflective piping runs along the seam between the carbon fiber and Cordura panels; reflective is good.The Elan has a zipper that opens the bag up like a tin of sardines. You can open it easily whether it's on the bike or in your hand; thanks to the Roller 2, it takes seconds to take off your bike and put in your hand. There is reflective tape alongside the zipper as well as on the bottom of the bag along the seams. The bag is just a simple single cavity with a Velcro compression strap to hold things in place; this is particularly useful when you're not filling the bag, as the stuff won't bounce around the inside, making distracting noises all during the ride. The tale of the tape with the Sci'Con Elan 615 Roller 2 Saddlebag is thus: it measures 9x13x10cm. The bag capacity is 615 cubic centimeters (37.53 cubic inches). It's Black with a Black carbon fiber panel.