They also have a decently smooth feel, unlike the more durable but rubbery TPU. PET is also a bit stiff, so it can't go edge-to-edge on phones with curved screens. If you want to go with PET, I recommend Tech Armor(Opens in a new window). And this kind of protector can be devided into many types with different aims and functions like PET Clear Film, PET Clear Anti Blue Light Film, PET Privacy Film and PET Anti Blue Light Privacy Film.
Thermoplastic Polyreuthane (TPU)
When you think of the screen protectors of old, you're probably thinking of TPU. TPU screen protector is a flexible plastic that's a huge hassle to install (it involves using a spray solution and squeegeeing out lots of bubbles), doesn't feel very smooth (thanks to its almost rubbery texture), and adds an "orange peel" type glare to your phone's screen. Still, it's flexible, so it can go edge-to-edge on any phone, it has better impact protection than PET, and it has limited "self-healing" powers for small scratches.
On the other hand, it comes in a few different styles depending on the look, feel, and features you want, for example there are TPU clear screen protector, TPU matte screen protector and so on. However, not all styles are available for all phones, and some phones don't have TPU options at all.