Fog Horn Sound Generator for Model Boats Admiralty Electronics Sound Modules come completely wired, including speaker and switch - simply connect your power source and install in your model. Smaller, larger and multiple speakers can be used to meet your space and/or volume requirements. 25mm x 65mm circuit board comes with a 50mm speaker and operates on 9 to 18V input power. Can be controlled by the wired mechanical switch and a servo or an electronic switch. Supplied in loop mode (sound cycles until switch is released) Complete instructions give full details on all options.