They keep the water out, but also allow heat and damp air to escape, so you avoid becoming to warm and sweaty. All shell jackets have a membrane developed to provide maximum protection for particularly demanding activities and weather conditions. Technical properties such as being waterproof, windproof, and breathable give the highest possible level of comfort. Shell jackets, waterproof hiking jacks, rain jackets and all-weather jackets - what we call them is as varied as the jackets themselves.
