The button is knitted plastic.
Such buttons are widely used in the textile industry when sewing knitwear, including clothing for adults and children, as well as bed linen. It consists of two parts: fasteners and caps. It is made of high-quality plastic, which, unlike metal, does not oxidize, does not change color and is not able to spoil the fabric. For lovers of creativity, it will also come in handy (to fix the product). The button is easy to install, even a layman can cope with such a task. This hardware can be used to replace old or missing buttons on your things.
It is acceptable to have a small amount of chips in the package, which helps prevent corrosion.