Yesterday 4-2-2024 the HVAC pre-filters at each of the 4 out station buildings along the arms were replaced with new pre-filters. The new pre filters are the same size (24"x24"x2") and filtration level (MERV-13) as the old pre-filters that were taken out. 
During inspection of the pre-filters an inspection was done on the "Main Filter Cartridge" which is the harder, more permanent, deeper, and heavier duty material type cartridge. It's installed in front of the pre-filter that is used for air filtration in the HVAC system. These are nearing the end of their life cycle. These will likely be replaced in the coming couple months.