Guhring - M4x0.70 Metric Coarse, Oxide Finish, Cobalt Spiral Point Tap - Modified Bottoming Chamfer, Right Hand Thread, 63mm OAL, 7.5mm Thread Length, 4.5mm Shank Diam, 6G Class of Fit, Series 5720

Modified bottoming chamfers are similar to bottoming chamfers, but they are longer and have more teeth. They are used for threading blind holes and can be found with ranges between 2 to 2-1/2 threads. Some modified bottoming chamfers are 2-1/2 to 3 threads.

Oxide, also known as black oxide or steam oxide, is a surface treatment that prevents chip building, galling and welding on the workpiece. It is commonly used on low carbons, stainless steel and ferrous metals.

Cobalt is harder than high speed steel and provides better wear resistance. It is commonly used on high tensile alloys.