Wool is the classic survival fabric for good reason: it insulates even when wet, resists fire rather than melting like synthetics, and is tough enough to last decades. In a heated-off house, a broken-down car in winter, or a cold night out, a wool blanket is dependable warmth that needs no power and asks nothing of you.
Unlike a foil emergency blanket, which reflects heat but tears and offers no real padding, a wool blanket is something you can wrap up in, sit on, or layer over a sleeping bag night after night. It's the reusable backbone of cold-weather preparedness.