We had bought a backpack for our son. He goes in the 3rd class and the existing satchel comes so slowly to its full capacity. We ordered the backpack in the size 26 liters. Unfortunately, we had to after delivery (performed via Amazon as always very quick) notice that the amended capacity fails even lower than that of the old satchel. More research on the internet revealed that the specified size of 26 liters are not related to the backpack. Instead, the size of 16 liters (backpack) + 10 liters (Turnbeutel) refers. Therefore, we need to send back the otherwise very well-made backpack unfortunately again.