ALPS Mountaineering Spring Lake +45
Here's what other sites are saying:
The Spring Lake is the "in-between" rectangle bag of the ALPS Mountaineering line. Unlike the Summer Lake bag 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 when you just need something tocozy up with.
With synthetic insulation, the ALPS Mountaineering Spring Lake 45 Sleeping Bag has the right amount of warmth for warm-weather camping.