For use on the SMVK video kits (and VK6). Monitors have 3 position call volume adjustment, camera recall contrast and brightness adjustment. a maximum of 3 monitors can used installed per call button ( or a combination of 3 monitors (3351), audio handsets (3111A) or extension sounders(512A). Requires 3980 mounting plate and 850K psu Specifications: Screen: 4" monochrome Buttons: 5 Lock button: Yes Camera recall button: Yes Service buttons: 3 Dimensions: 205.5mm (W) x 218mm (H) x 57mm (D) System: VK6, SMVK kits