ALPS Mountaineering Spring Lake Sleeping Bag -
The Spring Lake is our "in-between" rectangle bag.
Unlike the Summer Lake bag (#56544) that only has insulation on one side, the Spring Lake has 20 oz. of TechLoft+ on each side, or 40 oz. total. The single layer of TechLoft+ is sewn-thru, but a loose outer improves the thermal efficiency. The Spring Lake bag is great for those cool spring or summer nights.