We blend in 20% spandex for 4-way stretch and compression. All seams are flatlocked stitched to avoid skin abrasion for ultimate comfort. Features: 80% Polyester / 20% Spandex, 5.0 ounces per square yard 4-way stretch All seams flat-lock stitched Rash Guard protection Moisture wicking Odor resistant and Stain release for easy care