I know that I can do tests where you cover up the exhale filter and blow. I can usually get this one air tight or i break the seal if i blow hard enough
Also the test where you cover the filters with your hands. For some reason this one never gets air tight but im not sure if that is due to the filter or plastic casing around the filters. I've tried with many different filters and multiple masks. This would be where it seems like i haven't fitted my mask properly but ive never been able to get it air tight so I'm not sure if it is supposed to be.