Features2-way voice communication between the resident and visitor occurs through the unit's built-in speaker, providing clear, on the spot interactionDoor station mounts recessed into the wall using an NRKR300D rough-in, providing you the perfect fit during installationNuTone® outdoor stations are weather safe and designed to withstand rain and other elements, giving you complete confidence in the performance of the system, no matter what the weatherThe NDB300 series door speaker is for use with the NM100 and NM200 master stations onlyProjects 1-9/16 in from surface