These are made from 410 stainless steel, which is considered a martensitic steel grade that is magnetic and does have high strength and hardness. This kind of steel is used for steam and gas turbine blades as well a surgical instruments. A quick online search will verify all this. So these screws are excellent for many applications, including drilling through thin metals and woods. With the wide heads, they were perfect for attaching decorative panels of slats to my wall. Plus, the black coating has held up really well and the double-sided, magnetized bit was a bonus, along with the little case. I think this was a heckuva deal at 190 for $24.25.
