Compression set or Compression resistance
For foam products in shoe manufacturing, we like to know how long the foam will last in a footbed or shoe midsole. Simply put, the compression set is how much a foam will bounce back after being compressed. Compression set is measured in a percentage. A foam that resists compression could have a score of 4%, a foam that is badly damaged by impact may have a score of 45%.
Poor quality EVA will have a high compression set value. High quality PU foam will last forever with a very low compression set. Injection molded EVA, like this shoe, will resist compression set.