The 81 Series includes three models and can accommodate over 30 Atlas Sound baffles. The 81-8S is designed to mount 8" loudspeakers and has a square cut-out with a multi-position hole pattern to accommodate an extensive variety of round and square baffles including torsion spring and screw mount models. (See chart below for specific baffle model numbers.) Adaptability of the 81-8S also makes it ideal as a stocking item. Model 81-4 features a round cut-out and accepts 4" loudspeaker baffle Models 51-4 and 60-4. Model 81-8R, like the 81-8S, handles 8" loudspeakers but features a round cut-out that suits baffles mounting the industry standard Atlas Sound 95 Series enclosures. All tile bridges are constructed of 24-gauge CRS with an electrogalvanized rust-resistant finish.