Top quality product. We had 2 x 15cm numbers. I found that getting the numbers mounted "true and plumb" with each other in all directions was a little tricky using the pins and wall plugs provided. The answer was to simply drill the holes using the supplied template and then inject silicone (the type used around baths and windows) to fill the holes. The pins at the rear of each number could then easily be lined up and levelled. Masking tape could be used to temporarily hold them in place if required. Mine didn't even need this step. Using this method would be even more important if you had three (or more) numerals to mount. Helpful and friendly telephone service when I called. Highly recommended.