I leave PLA filament in my AMS for months at a time with no humidity control. Roughly 10% of the time I will find a bunch of broken pieces of filament in the PTFE feed tubes even though the roll it came off of is fine. This fixture allows you to insert filament samples from each new roll to see if they will break in a 7 - 14 day period, if they do, it is guaranteed they will break in the AMS if left there for a couple weeks