Ragnar Hi, You will know the thickness of the magnet so you simply remove that amount from the post it is to be mounted upon,
Rather more importantly I hope you realise that you will need to have an "Iron object" in the opposing post although I use another magnet which means reducing that post by the thickness of its magnet.
If you do use another magnet you will need a "North" if it is opposite a "South" or vice versa because of course a "North" facing a "North" will repel the other magnet as will a "South" facing a "South".
You might think that you only have to turn the magnet over to get the "North" "South" effect but the countersunk hole is only on one side so that instead of the magnet attracting the opposite magnet instead it is attracting the projecting screw head
