The Draeger D24-8101961 are tubes specifically designed to detect hydrogen sulphide (H2S) gas.

People use these tubes to detect the presence of hydrogen sulphide gas in the air. Hydrogen sulfide is a colorless gas with a strong rotten egg odor. It can be dangerous at high concentrations because it can irritate the respiratory system and even cause death in severe cases.

Industrial settings - workers in industries such as waste water treatment, oil and gas refineries, and paper mills may be exposed to hydrogen sulphide gas. These tubes can be used to monitor workplace air quality and ensure worker safety.
Environmental monitoring - environmental professionals might use these tubes to test for hydrogen sulphide in air or water around landfills, sewage treatment plants, or other areas where organic matter is decomposing.
Emergency response - first responders such as fire fighters or hazmat teams may use these tubes to identify the presence of hydrogen sulphide gas at a hazardous materials incident.