PET and PLA are the two most common transparent window films used in paper packaging. While PET is widely valued for its durability, clarity, and established recycling infrastructure, PLA attracts brands seeking renewable materials and compostable packaging options. This guide compares PET and PLA window films from a packaging buyer’s perspective, covering sustainability, recyclability, transportation performance, cost considerations, and real-world applications. It also explains when each material makes the most sense based on product requirements, distribution conditions, and brand sustainability goals.