When selecting outdoor jackets, the fabric technology is the most critical factor. You must prioritize Waterproof Ratings (measured in mm); for professional use, look for ≥10,000mm, while extreme conditions require 20,000mm+. Equally important is Moisture Permeability (Breathability), typically measured in g/m²/24h; high-performance jackets should exceed 10,000g/m² to prevent internal condensation. Ensure the supplier uses Durable Water Repellent (DWR) coatings that are PFOA/PFOS-free to meet modern environmental standards.