Product Details: Type RBKW Brand Cargo Carbide Material Cast Iron What Are Round Milling Inserts? Round milling inserts are cutting tool inserts with a round or circular shape, designed specifically for use in milling operations. Their unique geometry allows them to perform a variety of tasks effectively, making them a valuable addition to any machinist’s toolkit. The round shape of these inserts enables them to cut and mill with a high degree of versatility and precision.