Purchase 200 Window Jamb Extension Clips and all 1/2" and 2" screws required in bulk here.
Window jamb extension clips secure the jamb extension to the wall framing. The clips stop the Jamb Extension from bowing when foam or fiberglass insulation is applied and there are no insulation voids.
Install 1/2" screws to the Jamb Extension and 2" screws into the wall framing making sure the Jamb Extension is plumb.