The bag AUTHOR LitePack 13 with Alloy seatpost carrier. One main divided compartment with two expandable pannier side panels. Quick and easy fixation of bag on carrier. On the top is placed shoulder strap for easy movement. Expandable main and side compartments provides easy volume adjustment exactly as you need . Construction combines panels with EVA foam and flexible fabric for rigidity and protection. The perfect bag for the city commuter and for long distance cyclist alike.