It's structural silicone glass.
Is in the line of sight slim and sleek 2" or performance. Built on the strength and reliability of the flagship 1600 curtain wall deck, the curtain wall system 1620/1620 SSG is an excellent choice for low to medium height applications.The 1620/1620 SSG curtain wall system uses a silicone compatible elastomer for thermal break and can accommodate double pane insulated glass. Optional fiberglass helps architects and glazing contractors achieve even higher thermal performance Glaziers and installers can take advantage of their prior knowledge of the 1600 Wall System 1 and 1600 Wall System 2 curtain wall to simplify installation With one line low vision and design features that have been tested to US and Canadian standards, the 1620/1620 S Curtain Wall System SG lets you see less so you can see more.