I love these things. I have the same item from Yakamoz. They do their job, but the Greenlees do it better! They are tapered at the top and clean shavings much better than others. I cut 1/2" aluminum and 1/4" steel with no problem. They work better in my impact wrench than in a drill. The punch can be a bit slower than a drill and have better torque at low speeds.