French to English Tech/Engineering Construction / Civil Engineering fountain engineering

Hi!
This phrase is from the section on Filtration of a fountain engineering contract.

I am just not sure if it means "completely manufactured objects" or something else.... this is the french in context:

Il est considéré que les unités de filtration sont des objets manufacturés complets. Aucun assemblage du filtre sur le chantier n’est accepté. Elles doivent inclure toutes les pièces et équipements nécessaires à leur opération normale qu’ils soient ou non spécifiquement décrits dans les plans et devis.

This is my translation (minus the phrase):

It is considered that the filtration units are des objets manufacturés complets. No assembly of the filter on the construction site is accepted. They must include all the parts and equipment necessary for their normal operation, whether or not they are specifically described in the plans and tender.

Thanks!