The Casaval sleeping bag from The North Face is a synthetic 20 degree bag that is perfect for 3-season backpacking and camping. With a mummy design and a full side zip the Casaval bag will keep you warm while keeping you comfortable. The climashield CL insulation is an effective insulator and provides comfortable loft while you are inside. The Casaval Sleeping bag is not North Face's lightest 20 degree bag, but at 3 pounds it will not weigh a pack down.