Q magnets are a rare earth neodymium magnet and one of the strongest static magnets known. The magnetic field produced by even the larger Q magnets penetrate no more than around 2” or 5cm and even less on the side of the flux plate. Bringing sensitive medical devices such as pacemakers within this distance should be strictly avoided. Likewise keep your credit cards or any other magnetic storage device out of this range.
Placing any strong magnet on top of a spinning computer hard drive will likely destroy all data. But the newer solid state hard drives (with no spinning discs) don’t seem to be affected.