SILKWEIGHT: Excellent ultra thin rst layer for high aerobic all weather activities. Designed to dry quickly. LIGHTWEIGHT: Slightly heavier than Silkweight for added warmth, quick drying, used as a rst or second layer depending on weather conditions. MIDWEIGHT: Best all around weight. Great for stop and go activities. Quick drying with additional insulation and thickness for warmth. Great for stop and go activities in cold weather conditions. Can be used as rst or second layer. HEAVYWEIGHT: For colder weather conditions. Added insulation for greater warmth and comfort. BARRIERWEIGHT: Ultimate in warmth and comfort. Wind resistant, fleeced inner layer, dries quickly. Can be worn as first layer or outer layer depending on weather conditions and activities.