M's Lightweight R4 Jacket. Stay warm and stylish with this Patagonia men's black fleece jacket. Perfect for any occasion, this jacket offers comfort and durability and makes a great windbreaker. Good used condition, some signs of wear; no rips or tears. From Patagonia: Lightweight R4: 8.4-oz. Polartec Windbloc laminate combines a polyester micro-fleece face with R1 (Polartec Power Dry®) grid polyester on the inside. R1 Panels: 6.5-oz. 98%, 2% spandex (Polartec Power Dry) treated with a wicking finish