Down remains the best material for sleeping bag insulation when it comes to warmth and weight ratio. Most down bags in our lineup are filled with moisture resistant down, making them much less prone to loss of insulation in moist conditions. Synthetic insulation materials are affordable and easy to care for. A proper sleeping pad is essential, as the ground can suck away as much heat as your body can give out. Its not thickness alone that determines how much a pad will insulate - if air flows freely inside the pad, it can be cold. The warmest of our pads are thick and have synthetic or down insulation to trap the air in place.