When selecting hiking clothing, the 'Three-Layer System' is the industry standard. For the Base Layer, prioritize Merino wool or synthetic polyester for superior moisture-wicking and quick-dry capabilities; avoid cotton as it retains moisture. The Mid Layer should focus on thermal insulation, such as Polar Fleece or Down (700+ fill power). The Outer Layer (Shell) must feature a breathable waterproof membrane (like Gore-Tex or proprietary equivalents) with a Waterproof Rating of at least 10,000mm and a Breathability Rating of 10,000g/m²/24h for high-intensity trekking.