https://www.doorbird.com/downloads/datasheet/datasheet_d2102kv_surface_en.pdf
Doorbird Intercom D2102KV Surface-mounting housing (Backbox)
$328.74
Stainless steel V4A (salt-water and grinding dust resistant)
Stainless steel V4A (salt-water and grinding dust resistant), brushed (GTIN/EAN: 4260423871120, P/n: 423871120)
Fits only a D2102KV IP Video Door Station