The Mars atmosphere has a really low pressure and density compared to Earth. That’s why a specific device is necessary to gather and stock gases reclaimed from the atmosphere. The gas reclaimer helps you gather atmospheric gas from the outside and stock it for analysis.
Here’s a specific application: Players can set up an atmospheric gas reclaimer outside their habitat to stock carbon dioxide from the Mars atmosphere. Given Mars’ low atmospheric pressure, this takes a while. Using the in-game programming system, players can set an extraction frequency and quantity before the tool automatically transfers the gas collected to the rest of the circuit. This, for example, allows players to provide specific quantities of carbon dioxide to a MOXIE which turns it into oxygen.