The Women's Patagonia Nano Puff Vest is an insulation piece for keeping your core warm. Sleeveless and lightweight, this vest spans the seasons and extends your hiking and camping excursions. It packs into its own pocket, and the 60g PrimaLoft Gold Insulation Eco warms your center when the day turns chilly. Over a short or long sleeve t-shirt, alone or under a shell, it's ready to warm, even when the day turns damp.