You received stainless steel threaded rods along with your order. In order to drill the lid you need a (stone) drill with a diameter of the rods and installation glue. This installation glue comes from different manufacturers and is available in every DIY-store. We recommend the brand TEC-7. You can buy the glue in different colors or in a transparent version. To apply this glue you need a silicone spray-gun.
To facilitate the installation of the lid you will need a piece of cardboard as well that is a bit larger than the lid.
How do you proceed?:
Turn the threaded rods (pic 2) in the thread busses (pic 1) which you can find on the back of your mailbox lid.
Turn the threaded rods completely in the threaded sleeves. The result must resemble picture 3.
Put the lid upside down on the workbench (the threaded rods facing up), preferably on a soft sheet to avoid scratching the lid.
Push the piece of carton over the threaded rods.
Turn the lid over (with the piece of cardboard still over the threaded rods and draw with a pencil the contours of the lid over the piece of cardboard.
Remember to take into account the norms of the post (in Belgium) for the position of your mail slot.
Make sure the hole is large enough to fit the entire flap and spring mechanism. Draw the contours of the mechanism on the carton as well to verify this.
Slide the piece of cardboard over the threaded rods.
The piece of cardboard now functions as drilling jig.
Place the piece of cardboard against the wall where you want to attach your lid. Adhere it with tape if necessary, check with a level whether the contours are upright.
Drill the holes right through the drilling jig.
Vacuum the holes (or blow the dust out of the holes with a straw).
Spray a little installation glue in every drilled hole.
Push the lid with the threaded rods in the holes up to the threaded sleeves.