You need to be careful during sewing, since generally many parts of the sewing machine (needle plate, sewing foot, needle) are ferromagnetic and the magnet may adhere to them.
Thanks to the plastic cover, the magnet can be directly sewed onto the fabric.
Application: A tailor sews a blouse for an older woman. She should be able to open and close the blouse with one hand. This is where sew-in magnets come in handy as an alternative to buttons.
One magnet in plastic cover each will be placed on both sides of the blouse in between two layers of fabric and then carefully sewn in.
When they are sewed-in, the magnets are practically invisible.