These drill bits are not as advertised. In the description, HSS stands for steel, plastic and wood. "Low carbon steel and gold paint for wood, plastic, or foam" should have read on it. I was cheated on. I got what I paid for with the cheapest metric drill bits. Attempting to pierce 304 stainless steel will dull, sooty and bend or break them. Walmart's cheapest heavy-duty HSS bits go through the same 304 stainless steel, but Walmart doesn't sell 2.5mm or 3mm bits. Attention buyers, only wood or plastic.