There are two types of window film in general: Absorptive and Reflective.
Absorptive Type absorbs heat into the material itself. Common types include Ceramic film, ATO (Antimony Tin Oxide) & IR Absorber films.
Ceramic film is the best-performing absorptive type, offering durability and the best heat insulation.
ATO (Antimony Tin Oxide) performs well in handling far-IR but is weak when dealing with near-IR.
IR Absorber film is the lowest quality of all that is made from organic compounds that degrade when exposed to sunlight. It would provide high IR Rejection up to 95% in the beginning, but would possibly degrade to 10% within a year.
Reflective Type normally uses metallic material coatings to reflect heat. The common materials used are silver, gold, and other precious metals. They have a mirror-like finish and reflect heat effectively, but also block other radio wave signals. Normally, reflective-type products are expensive and are more difficult to install.