The NF300DWH Door Speaker Retrofit Frame is Used in Retrofit Intercom Installations When Replacing a Non-NM Series NuTone Door Station. This Retrofit Mounting Frame Fits the NDB300BB, NDB300AB, NDB300WH and NDB300N Door Speakers. NuTone NF300DWH Door Speaker Retrofit Frame For Projects: 1-9/16" with Door Speaker Replacement Installation, Use Existing Rough-in