Carbon dioxide absorber for a rebreather

A closed-circuit breathing apparatus comprising:

• a breathing tube;
• and
• a carbon dioxide absorber, the carbon dioxide absorber comprising:
• an inlet;
• an outlet, the inlet and the outlet being connectable to the breathing tube;
• a flow duct gas-tight connecting the inlet and the outlet;
• carbon dioxide absorbing material arranged in the flow duct to absorb at least some carbon dioxide contained in a breathing gas stream sent through the carbon dioxide absorbing material;
• a housing enclosing the flow duct in at least some areas;
• a window element arranged at the housing;
• and
• a display element arranged movably in the flow duct, the display element being visible from outside of the housing through the window element and/or radiation reflected by the display element exiting to the outside of the housing through the window element, wherein a distance between the window element and the display element varies as a function of a quantity of carbon dioxide-absorbing material arranged in the flow duct.