The quality of a wool felt hat is primarily determined by the purity and density of the wool. Look for 100% Australian wool as a benchmark for premium texture and durability. High-quality felt should feel firm yet smooth to the touch, without visible thinning or 'pilling.' Check the 'X' factor rating (e.g., 2X, 5X, 10X); while not standardized across all manufacturers, a higher number generally indicates a higher percentage of fur or finer wool blend, resulting in better water resistance and shape retention.