TPU stands for Thermoplastic Polyurethane, and it's the industry standard material for quality ski goggle frames. The big advantage is that it stays soft and flexible even in bitter cold, so your goggles conform comfortably to your face all day on the mountain instead of feeling stiff or creating pressure points.
Unlike rigid plastic frames—which can become brittle and even crack in extreme cold—TPU bends without breaking. That flexibility also matters if you swap lenses for different conditions, since the frame needs to give slightly to release and secure the lens properly.
You'll find TPU frames across all price ranges from reputable brands, so you don't need to splurge to get this feature. It's really a baseline expectation for any goggle worth buying. If you come across goggles without TPU, they're likely budget models with rigid plastic that won't hold up or feel comfortable in real winter conditions.