This Navien 1000mm standard horizontal flue kit is designed for installing a horizontal flue system that is a fixed 1000mm (1 meter) in length, but is cutable to the desired length. This kit is typically used for gas appliances such as boilers, where the flue needs to exit horizontally through an external wall. The kit ensures that exhaust gases are safely expelled outside the building, preventing any buildup of dangerous gases indoors.

In summary, a 1000mm standard horizontal flue kit provides all the necessary components for a secure, efficient, and safe installation of a horizontal flue system, ensuring proper venting of exhaust gases from gas appliances through an external wall.