5 season sleeping bags are designed for use in cold and extreme conditions and are the warmest sleeping bags you'll find. Of course seasons can be different depending on your destination, so many people judge the performance of their sleeping bag by its comfort temperature. The comfort temperature provides a more of a universal indication of its warmth and suitability for your chosen activity and where you will be using the sleeping bag.
5 season sleeping bags (of 4+season sleeping bags) are perfect for expeditions and generally include features such as insulated baffles, durable water repellent shells and technical insulation that performs well in damp conditions to maintain its insulating properties.
I have been looking for a pure cotton sleeping bag liner for a while but many brands say cotton but then it turns out to be polycotton. However this one from Lifeventure is 100% cotton like I wanted :-)
