I could not understand these bits. I have a 25ft implement trailer that I fixed the floor on and used these bits to drill holes for the floor fasteners. The first punch lasted much longer than any normal punch. The three of us who worked on this trailer talked about how phenomenal these tracks were. Then. Some drills didn't drill a single hole until they burned out, others broke in two halfway through the hole. Each of the 10 parts was as different as the kids from The Brady Bunch! If all 10 bits were the same as the first bit I used I could use 3 bits on almost 200 holes. Instead, I ran out of beats before I was done. If this company had quality control to make every bit the same as the first bit I used, I would buy boxes of every size bit they make and pass my remaining bits on to my grandkids!