Not too big, not to small, just optimal is how I would describe the Trekking Pro top tube bag. The Trekking Pro provides an adequate 1.2 liter capacity, which is good enough for a day trip. Moreover, we understand the importance of space management, and have included two additional pockets on both sides. This way the cyclist can have better access for items such as energy gel, Allen key or snack bar. In addition, on the left pocket we added an extra multiband in case you need to store your mobile phone. This will prevent your phone from falling off while riding. For internal organization, we have included a mesh pocket.