For the pack size, this sleeping bag liner is hard to beat. I initially purchased the liner for an extra bit of warmth while camping in the cooler days of spring and fall - and it works great for that purpose. However, I also found that it works well for summer camping. When the weather is on the border of too warm for full sleeping bag coverage, but not warm enough to pull yourself entirely out of your bag, this liner is a savior! Just partially peel off your sleeping bag and let the liner help modulate your body temperature.
After writing this review I am purchasing another for my wife. Any product that makes my wife happy definitely earns five stars!