Louroe Audio Monitoring ALA-4TB is a four zone alarming base station with two-way listen and talkback designed to provide sound activated audio monitoring, when interfaced with Louroe speaker/microphones. Each zone has a variable threshold level (set by installer or owner) based on frequency and sound pressure that activates when a sound exceeds the set threshold level. A short alarm and lighted LED identifies the zone, along with a relay contact for activating a camera or other annunciation. Model ALA-4TB is rack mountable. Compatible with all Louroe speaker/microphones. For two-way communications. Dimensions: 19 inch W x 5 1/4 inch H x 9 1/2 inch D