It’s a pad that reflects body heat back up into the mat, making it all warm. That’s atop a shelving thing that is right next to the window. Also right next to my bed. Between that and the hammock hanging off my headboard that doesn’t reflect heat but has the same angle to the window but opposite side, she spends a lot of time there. She’ll also drag me to bed so she can go up and relax comfortably knowing that I’m nearby lol