Armstrong recommends the use of #435 Stabilizer Clips for 3/4" and 1" thick panels and #436 for 1-1/2" panels. These clips are embedded into the edges of the panels. The clips saddle over the suspension system, and serve to prevent the grid from moving away from the panel edge. Panels longer than 5' and up to 8' in length should have one clip installed near the midpoint of each long edge. Panels 8' and longer should have two clips placed at one-third points along the long edges.
WARNING:Cancer and Reproductive Harm - www.P65Warnings.ca.gov