Trim rings allows installation of control contractor ceiling speakers into existing ceiling speaker cut-outs that are larger than the speaker's normal cut-out size. The maximum cut-out size accommodated depends on the installation configuration. Uses single trim ring for cut-outs up to 200mm (8 in) in diameter for control 24C/24CT and up to 260mm (10 in ) for control 26C/CT, the speakers can be installed using a single trim ring on the bottom of the ceiling surface and using the stock C-bracket (included with the speaker) on top of the ceiling surface. Uses the tile rails (included with the speaker) improves stability. Larger cut-outs, up to 280mm (11 in) for either speaker model can be accommodated by using two trim rings one on the bottom and one on the top of the ceiling surface. Using the C-bracket and tile rails (included with the speaker) above the top trim ring further improves stability.