argon gas window fill 3

https://kilo-wiki.win/index.php/What_to_Look_for_in_a_Window_Glass_Warranty_Before_You_Buy

When you see argon gas window fill on a window label, it means the space between the panes is filled with argon instead of regular air. Argon is denser than air, so it moves less inside the gap, which reduces heat transfer through the window. This makes the window more energy-efficient, especially in colder months. It's a pretty standard upgrade now, and you won't notice any difference in appearance—just a quieter, warmer house and lower energy bills.