F-350-24 high output buzzer, 24VAC, 0.9A, 100dB output at 10ft. Mounts to a standard 4-inch square box. Optional F-3014 weatherproof box is available. These buzzers are easily controlled using any of the MC series master clocks, or for smaller schools or factories the AP21LV time switch can be used. ATS provides optional, 2/4A built-in, bell transformers for some of the MC series master clocks. External mounted transformer assemblies such as the 8901-1821 and the 8901-1411 can be used for larger systems.