There's literally hundreds on Amazon for under $10 for a pack of 3-4 usually. I like the ones that have the install tray that you place over your phone and it applies the protector. It's a no-brainer easy install.
yeah it's a plastic film and they have screen protectors separately for every phone, so probably they are custom designed to fit the respective phone. my screen protector is nearly 6 months old, apparently there's no bubbles and no yellowing