Window film that has been installed on glass for many years can be difficult to remove, especially if the adhesive system is CDF (water-activated) and forms a chemical bond to the glass.
It takes a lot of elbow grease and the right blade system to remove that old film. A 4″ Carbon Scraper Blade is just the right system.
Pack of 10 blades. Handle (GT104) sold separately.
Be sure to exercise caution when using a blade. Remember that any blade can scratch glass, even if labeled as safe for glass.