Mostme 200 Set 2.25 inch Button Maker Kit, 58mm Supplies, Includes Metal Pin Back Cover, Shells, Blank Paper & Film

Are these metric or standard buttons? Please state if they are for 58mm buttons or for 2.25 in buttons. The two are not interchangeable.

What metal are these made of? Stainless Steel?

300 sets, will this make 300 or 100 buttons?

Do these come separated in bags or thrown in all together?