Mountain equipment helium 600 sleeping bag left zip low in weight and warm enough for early spring and late autumn use at higher altitudes or northern latitudes features helium tm 20 outer shell is very light and highly breathable 582g of 90 10 pure duck down with a minimum fill power of 700 alpine fit maximises thermal efficiency slanted box wall baffles throughout mid level side seams 5 baffle anatomically shaped hood 4 baffle anatomically shaped and offset foot box full length