Because they don't allow the earring backings to fall by motion, screw backs are the most secure type of earring backs. Also, the threads on the rod prevent the nut from sliding down. Similarly, secure lock-backs are also considered safe. Since these earring closures have their own clutching mechanism, they hold on to any earring well. Plus, they make perfect earrings to sleep in or any physical activity as they secure your earrings in place. They might not be the most stylish, but they'll guard your earrings.