Review on Save Money And Time With 30 Pack SK5 Steel Utility Knife Blades - Heavy Duty Replacement Razor Blades For Box Cutters With Convenient Plastic Case by Michael Hicks

I bought these because the price for the amount of blades was good and they claim to be made of SK5 which is fairly good steel. They come sharp but a little burred. If you just want em to cut cardboard, plastic, and other soft materials they're great. But if you do construction and want heavy duty blades for hard use these aren't good at all. Stripping wire before a pull and doing other hard tasks they chip out and roll over worse than any I've ever seen. Just not heavy duty.