That air core, while a decent deal, will literally suck the warmth out of your body. Not a problem unless lows drop below the high 40s or so. I have one and use it but wish I would have gotten something with at least some R value. Even in a 32 degree bag I can feel cold on that pad in the mid 40s. The issue being that the insulation in the sleeping bag doesn't work when it is compressed between the body and the pad. Planning to replace it with a Klymit pad that allows a bag to insulate a bit from below. This is one place I would not skimp again if I had the choice. It is much easier to unzip your sleeping bag to let out some warmth than it is to deal with a cold back in the middle of the night until the sun rises. Spending twenty more dollars to upgrade to the insulated version is certainly worth it if you ever think you might spend cool to cold nights outdoors...