Superior shelving unit: SPCC Cold-Rolled steel sheets, pressed to 1.2mm thick, make up the high-strength construction of the Networx rack shelf. Maximum airflow: Help always keep vital equipment cool with precision placed vents for maximum airflow. Precision. Perfection: The precision design makes it the perfect fit for all 19” Racks and can accommodate a variety of A/V, networking, and musical equipment up to 44 lbs.