I have bought about 10 of these bits. They ship very quickly. Cheaper than what I buy at my local hardware store. I love these beats. They can easily break if you are not careful and don't know how to use them properly. They are designed to operate at higher speeds when used on metal. I use them almost every day to cut stainless steel. They work great π. They're really great for softer metals like brass, aluminium, plastic and even at lower speeds. Just a great hit. Diverse application possibilities. If in doubt, take out the tungsten. Lately for me and I'm pretty picky about beats. Remember that at high speeds light pressure is required. Take your time and they won't let you down. Will order from here whenever I need new ones. Highly recommended.