Chicago Metallic® G90 Exterior Grade Systems are available in a heavy-duty design, for both standard 15/16" exposed grid and 1-3/8" drywall suspension systems, and is built with HDG 90 steel. Ideal for exterior applications, this drop ceiling grid features seismically approved stab-end cross tees for quick and easy assembly. Our entire line of Chicago Metallic™ grid systems are third party certified to meet ASTM standards.