What Our Gearhead(R) Experts Are Saying:"I throw this vest over a base layer on cool mornings or under a shell when conditions shift-it breathes great, insulates just enough, and never feels bulky on the move."From early morning trail approaches to summit transitions, the R1 Air Vest gives us core warmth with none of the weight or bulk. Made with Patagonia's signature 100% recycled polyester jacquard fleece, the vest leverages hollow-core yarns and a zigzag knit to wick moisture and trap just the right amount of heat. With a slim, low-profile design, it layers seamlessly under a hardshell without sacrificing mobility. The full-zip front offers quick ventilation, and a zippered chest pocket keeps essentials close. Bluesign(R) approved and Fair Trade Certified(TM) sewn, the R1 Air Vest is a minimalist layering piece that punches above its weight on technical missions.