The 9155013 is a 3-Module Flush-mount Frame for use in completing a 2N Helios IP Verso Modular Door Intercom system. The 2N 9155013 3-Module Frame can be used with either a Verso Basic Main Unit + 1 additonal Module or with 3x Additional Function Modules. Having chosen your Verso Basic Main Unit (Part Number 9155101 or 9155101C), you can choose from a range of Surface-mount for Flush-mount Frames, Back Boxes, Additonal Function and Accessories to create an easily self-assembled, professional grade Door Access Unit. The 9155013 Verso Frame should be used with Back Box Part No. 9155016.