Federal signal Vibratone® heavy duty product line utilizes a modular approach to combine gongs and mechanisms allowing for greater flexibility and selection. Three gong sizes are available, the model A4 is four inches in diameter, the model A6 is six inches in diameter and the model A10 is ten inches in diameter. Each larger gong produces a different tone and a higher dBA output. Vibrating bells produce a continuous ringing sound when voltage is applied. Federal signal Vibratone® bells can be used in any industrial application, whether to signal danger or for start and dismissal. A variety of mounting accessories will accommodate almost any environment.