After trying these knurls I couldn`t be more impressed .They fit perfectly on my indexable insert holder and produce a clean and precise knurling pattern on my metalwork. the blades are easily replaceable too, making maintenance hassle-free. However, they can be a bit pricey compared to traditional knurling tools. Overall, HHIP's Indexable Insert Holders with Revolving Knurls are a great investment for any metalworking enthusiast or professional..