Bernard Hats Custom Hats come in 3 quality beaver blends – 5X, 20X and 100X. 5X is a blend of about 5% beaver with rabbit and felt. 20X is 50% beaver and the 100X is pure 100% beaver fur. Beaver Fur Felt is dense and virtually waterproof and consists of pure beaver or rabbit/hare fur blended with felt to produce a material that lasts 5-10 times longer than wool felt. That is why some of our vintage hats are in excellent condition and are as good as new 60 years later! A fine beaver fur felt or blended fur can be re-blocked and shaped any number of times which is why it is the best material to manufacture high quality hats.