The Just My Size Microfiber Mesh Ultra Light Brief Panty - 5 Pack 1210U5 is ventilated knit for airflow and has a 4-way stretch fit with Cool Comfort wicking. Just My Size's Microfiber Mesh Ultra Light Brief Panty - 5 Pack is made of polyester/spandex. Please note this is a FINAL SALE item - sorry, no returns, exchanges or refunds.