20mm dia x 5mm thick x 5.2mm c/s Zinc Plated N42 Neodymium Magnet - 8.3kg Pull ( South ) ( Pack of 2 )

Countersunk magnets have a central hole which allows them to be fixed to non-magnetic surfaces with a screw. If your project requires magnet-to-magnet application, use North pole with South pole magnet to avoid the magnets repelling.