House numbers come standard with countersunk holes and stainless steel screws for fastening. An aluminum mounting bar can be used to achieve the floating look and for a level mounting surface. No matter how many numbers you have, only 2 fasteners will be going into your exterior. Mounting bars are custom made to the length and orientation you plan to place your numbers. Numbers ordered in a patina finish will have the mounting bar and spacers painted to match. Spacers are 3/4" (19mm) in depth. Double sided 3M tape, suitable for our North American climate is applied to the back of each number in the orientation requested. 3" (76mm) screws are provided.