Perfect to extend your bags season
I don't have a need for a winter sleeping bag but I do like to camp in the shoulder seasons when temps can drop down to the 30's. I picked up the reactor liner for myself and the reactor plus for my wife. If you really want the extra warmth i'd grab the reactor plus. Its noticeably thicker and does add substantial warmth (Sea to Summit suggests it adds 20 degress while the reactor adds 15). Again, extra comfort, keeps your bag clean, and adds warmth for 9oz. I was on the fence on if this was worth $60 but it is totally worth it. You can also use it as your bag in the summer or take it on travels when you don't trust the bed sheets.