The panel is surface mounted through all the holes on the outer flange. Review installation drawings before installing. The number of mounting holes will vary with the size of the door. Surface mount, 16mm (5/8″) deep door assembly. Ideal when objects (pipes, etc.) interfere with the standard inner door frame. Quick installation, surface mounting holes. Exterior appearance is compatible with the non rated and fire rated access Linhdor access door line, so uniformity of design is maintained when the doors are installed in the same building.