Neodymium magnets are very strong magnets and they are safe to handle. The one area where these magnets are not safe is if you swallow them, the removal requires surgery in most cases. Keep these magnets away from young children and pets. You can stack the magnets together safely, it just makes it hard to pull one magnet off the stack. Also, keep these magnets away from magnetic strips on credit cards, cassette tapes, computer floppies and similar recorded items because the magnet will erase the data.