IQShield Liquid Skin 2-Pack ($8)
Another excellent choice for smartphone screen protection is IQShield. They're one of the pioneers in the "liquid skin" space. You'll get two screen protector for one low price, and they're easy to install too.
IQShield uses a Smart Skin that perfectly fits the Galaxy Note 9 screen. You'll get a precision-cut easy installation tray and a bottle of applicator liquid to complete the installation. This way you can slide it around until you get the perfect fit, just how you want it, and then let it dry.
They use a military-grade film similar to most other films in the industry, and that's a good thing. We've used IQShield in the past and enjoyed the results. You get two, and they have a lifetime warranty. This is also one of the highest rated options on Amazon.