Depending on the felt quality and amount of beaver utilized in construction, hat makers traditionally graded hats on a scale of 1X–10X. Hats between 1X–5X were usually made of wool and or hare with a small amount of beaver, if any. A 10X hat contained 100 percent beaver.
Today, hats are marketed with ratings from 1X to 10,000X, felt and straw alike. Although the X Factor seems to be more of an advertising tool than any real indication of the percentage of beaver (for felt) or natural fiber and the tightness of weave (for straw). There is no standardized system in place, and hat makers vary significantly in their use of the X’s—with higher X Factors sometimes describing the hatband quality instead of the hat material itself.
Our Advice: Use your own visual and tactile senses and ask a lot of questions. Quality material and construction do not lie.