Armstrong Suspension Systems are are the only systems that use rotary stitching for added strength, the SuperLock clip for the most secure connection and fast, accurate alignment and the patented PeakForm profile to increase strength and stability. The components of Armstrong Suspension Systems work together to provide reliable performance for your installation. Main beams are used with accompanying cross tees and wall trim for a complete, tested, tried & true installation. All components meet seismic requirements when installed per International Code Council (ICC) ESR-1308. Armstrong Prelude XL Exposed Tee Systems meet the demanding needs of today's commercial and residential interiors.