A fellow hiker on the Pacific Crest Trail raved about his so I had to get one too.Great design & materials. Fine craft-work. Good price. Fast shipping. And a good cause! Thick enough to protect your bag and to add a small amount of warmth but thin enough to use alone in warm weather and not to add much bulk if constricted at bottom to line a mummy bag. And WAY easier to clean than a down sleeping bag. Great customer service!