ACD (Air Cool Designed) products are made with the highest quality ventilated materials, providing durability, protection, and constant air flow. The outer mesh is vented for air flow and is durable, heavyweight. The Shok-Sorb foam is ventilated for airflow. The knit lining is vented for air flow and is micro knit for comfort. This technology lets cool/dry air in and lets hot/moist air out!