Panasonic KX-NT543 Quick Reference Manual page 25

One screw here
WALL MOUNTING TEMPLATE
1. Drive the screws into the wall as indicated.
2. Hook the unit onto the screw heads.
Note
Make sure to set the print size to correspond
with the size of this page. If the dimensions of
the paper output still deviate slightly from the
measurements indicated here, use the
measurements indicated here.
One screw at either point