The filter (T1313) used on the 999 is made for us to USDA specifications. It is rayon with polyvinyl acetate binders. It’s basis weight is between 2.48 and 3.03 oz/yd². Thickness is between 17.0 and 21.0 mils. Air Perm (cfm / sq ft.) is between 135 and 235, with 185 being the usual. Wet Mullen Burst is 21.0 to 24.0. No micron rating is published. We do know this filter usually withholds 75µm, as required.
The filter used on card number 32800 is Reemay 2024 and is USDA accepted for food use, but not for milk testing. It is spun bonded polyester with a nominal basis weight of 2.1 oz/yd², and a thickness of 12 mil. The Mullen Burst is 48 psi. Air permeability is not listed. No micron rating is published.
No filter mill is supplying a micron rating anymore, due to the many, many variables of material being tested, pressures used, etc.