Federal Signal's 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's 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.