Provides the most room to stretch out but is less efficient at holding heat because of excess air space. Best for warm-weather car camping.
Offers the best warmth-to-weight ratio and is highly compressible, making it ideal for backpacking. However, it is more expensive and loses its insulating properties if it gets wet, though "hydrophobic down" treatments can mitigate this. how to buy a sleeping bag
Insulated tubes along the zipper and around the neck to prevent warm air from escaping. Provides the most room to stretch out but