A ceiling suspension system that includes a plurality of acoustic panels that are configured to be installed or attached into openings of a grid formed by main runners and cross runners of the ceiling suspension system. The acoustic panels include a plurality of main blades that extend in the same direction as the main runners and cross blades that extend in the same direction as the cross runners. Two or more of the main blades comprise a kerf in a first lateral edge of each main blade. The kerf comprises a first slot and a second slot that form a stepped configuration.