Hey @Luisvbo06 , I assume that a mini-ITX or micro-ATX is installed for this size.
Unfortunately, I can't find any exact details. otherwise, contact the manufacturer directly.

But it is a prefabricated PC, why do you need to know that?
Or do you have this one and want to upgrade it? If so, you can measure the mainboard and give it to me so I can tell you what's inside.

Greetings