Roto Molded 20" deep rack frame with a molded valance and a rubber gasket on both the front and rear doors for water resistant protection with elastomeric shocks.SKB catalog page (PDF): 20 Inch Deep Series iSheet
Roto Molded Process of forming powdered plastic in a large oven in aluminum molds that rotate on two axis to evenly melt and distribute the plastic giving an even density and strong corners.