The I-9403 is a detachable, surface mounted sounder and strobe while the I- 9404 is identical in appearance and features to the I-9403 but without strobe element. The audio efficiency and sound distribution generate over 85 dB at 3 meter distance giving an excellent audibility from the device location. Using six highlights LED’s for high intensity visual alarm to warn the people. The GST sounder series are convenient plug and turn installing method, two part construction with base mounted termination allows easy installation and avoiding the wiring and connection problem associated with traditional sounder.