It's been years since I've actually been in a store that sold hats so I'd forgotten that felt hats are often described as a '8x' or a '6x' or whatever, describing the quality of the felt.
I know Marc and Steve are busy with hats so I thought I'd pose the question here: what 'X' grade would an AB hat be? Or an AB Deluxe?
An AB would be 100% beaver. No X involved. It used to be many decades ago that the X would denote a certain percentage of beaver content in hats. Nowadays, it doesn't mean squat. Hat companies use the X as a marketing ploy, not as any real indication of the beaver content in hats.