From Lululemons website… Designed for Running Lightweight, Swift Fabric… Lightweight Four-way stretch Sweat-wicking Quick-drying Liner is lightweight, sweat-wicking, and quick-drying with added Lycra® fibre contains recycled polyester made from repurposed plastic waste High Rise, 4" Length Product Features… Built-in liner offers extra coverage Connected gel pockets on the waistband gives you flexible storage options Secure back pocket Continuous drawcord