Back length adjustment for a backpack, rear wall of a backpack and backpack

A back length adjustment for a backpack comprising:

• a setting element that is firmly connected to a rear wall of the backpack via a connecting device;
• a sliding body comprising:
• a shoulder strap region comprising a fastening region for connection to shoulder straps of the backpack;
• a guide region;
• and
• a setting region that extends in a longitudinal direction of the rear wall of the backpack, wherein the setting region is configured to interact with the setting element so that, in an adjustment state in which the setting element is in an adjustment position, the sliding body is displaceable with respect to the setting element, and in a use state in which the setting element is in a setting position and the setting region is connected to the setting element in a force-fitting and/or form-fitting manner, the sliding body is set at the setting element;
• and
• a guide device comprising a guide that interacts with the guide region and which is part of a support structure of the rear wall of the backpack,
• wherein a guide seat formed on the sliding body cooperates with the guide of the guide device so that the sliding body is displaceable along the guide.