There are two models in the scene, the only difference is in the material.
There are no additional plugins.
The model is created in millimeters
The models are called by their proper names; when downloading, you can select the option you are interested in.
The model is configured for Corona renderer AND V-Ray

Dimensions
Height 500mm
Width 180mm
Depth 78mm
https://www.eichholtz.com/en/wall-lamp-nuvola-l-115743.html 
https://www.eichholtz.com/en/wall-lamp-nuvola-l-116392.html 

For Corona render, it is recommended to install version no lower than 1.5, since the glossiness of the materials is adjusted taking into account PBR

Those who work in a V-Ray version lower than 3.1, be careful, in the materials in the BRDF section there is Microfaset GTR (GGX), if your version is older than 3.1, then the BRDF field will be empty. Choose Blinn, Phong or Ward – whichever is preferable for you