This is a National doorphone exterior unit, rarely seen. It has been disassembled and serviced, and its operation is guaranteed. Dimensions: Width 9.9cm, Height 13.8cm, Mounting hole spacing 11.9cm Rear protrusion: Width 4.8cm, Height 7.2cm It is compatible with National doorphones before the introduction of camera-equipped models, such as the VL-568 series, and can be replaced. How about using it as a replacement? Doorphones from this era used reed relays in the push buttons, making them resistant to rain. Thank you for viewing.