M&S NM100 Intercom Update MC300 Retrofit Master 9 Station Kit (1) Music/Communication Retrofit System Master (3 and 4 Wire) (White) - 15.25 x 5.32 (1) Master Station Rough-In - Wall Housing 14 1/2 x 4 5/8 (1) Master Only Retrofit Frame - White (17 1/2 in. x 10 5/8 in.) (9) Indoor Remote Station (3-wire) White (5 1/2 X 5 1/2) (9) Indoor Remote Station Retrofit Frame - White 7.5 x 10