I'd probably be willing to wager a nickel or three that Amsoil doesn't manufacture filters. You can buy a lot of private label filters with names ranging from fluid suppliers to parts suppliers to equipment builders, but the filters are manufactured by Wix, Fram, Purolator, or some other company that makes filters.
Amsoil can go to one of these companies and ask about what sort of options exist with regard to media type, pore size, support & flow configurations, just like anyone else who wants to market a private label filter.
But let's not kid ourselves that whoever Amsoil hired to make their filters gave them access to some special, super-secret combination of materials & design that's not available to anyone else who walks in the door. And don't imagine for a minute that design is better than the manufacturer's own top-of-the-line filter.