Mountain equipment snowline sleeping bag left zip their lightest expedition class sleeping bag ultralight when used alone but with enough room to accommodate clothing when pushed to its absolute limit features gore thermium tm 10d outer shell is durably light highly breathable and rain resistant 831g of 90 10 russian goose down with a minimum fill power of 800 expedition fit with exl system is both roomier and has improved loft and thermal efficiency v chest and foot baffles tra