Model 300GC SelecTone® Amplified Speaker is designed to produce crisp, clear tones, digital voice messages and live public address in harsh environments with high ambient noise levels.The internal circuitry, tone module, and gain control are contained in a housing constructed of die-cast aluminum. All surfaces are sealed with powder-coat paint. Dust- and moisture-proof gaskets provide protection from the elements.SelecTone Amplified Speakers are used individually or as part of a plant-wide emergency notification system. Model UTM Universal Tone Module with 32 tones, or model TM33-SD Custom Tone Module is plugged into a single SelecTone Amplified Speaker for stand-alone use or into a SelecTone Command Unit for plant-wide signaling.For plant-wide signaling, a Connector Kit is installed into each SelecTone Amplified Speaker and wired to a central controller. SelecTone Command Units and CommCenter® Digital Message Centers broadcast tones, voice messages, melodies and live public address to an unlimited number of SelecTone Amplified Speakers.