The Holy Grail of Hammock Camping. Pack less with the Grand Trunk Evolution 20 Down Hammock. The Evolution integrates a sewn-in synthetic fill sleeping bag with a hammock, truly a match made in heaven! Integrated sleeping bag technology provides the perfect combination of relaxation and warmth. Dont worry about a bag bunching up or dealing with an under/over quilt. This patented product gives you a range of motion while staying cozy in a blanket of comfort.