Castelli crafts the Insider Jersey specifically for the rigors of indoor training--situations in which cyclists are putting out maximum effort in spaces with limited ventilation and airflow. In order to overcome these limitations, Castelli constructs the jersey from a porous 3D Mesh fabric that lets air move as freely as possible to help you stay cool, regardless of whether you're spinning in the garage, basement, or muggy spare bedroom. This airy material also wicks moisture better than a traditional cycling jersey, keeping sweat at bay to help you stay dry and comfortable when you're cranking out watts. Despite the meshy construction, Castelli paid special attention to not make the Insider Jersey too transparent, meaning it would make a great outdoor jersey for summer rides when the temperatures are approaching triple digits and beyond.