Indexable square-shoulder end mills cut in two directions (laterally and axially) to make 90° angled cuts in shoulder milling operations. Sometimes called 0°/90° mills, they have flutes that carry chips away, and they have seats at the tip of the flutes to hold cutting inserts. They mount to a milling machine and use replaceable, multi-edged cutting inserts that can be rotated (indexed) to expose a fresh cutting edge when the old one dulls. The inserts can be replaced with new ones of the same type or different types without removing the end mill from the machine. Indexable milling tools require fewer tool changes than solid tools in high-volume metalworking and fabrication applications with high speeds, high feeds, and difficult-to-machine materials.