What is the specific content of the four-way buckle?

Snap button, also known as hood button, a kind of button. The main problem of making a snap button is the mold. If the mold for the top and bottom buttons is correct, you can smash it with a hammer. At least you need a mold with a concave edge, otherwise it will definitely be useless. It is a machine with a very simple principle, from hammer to die, to mass production and machine pressing.