Inserts are locked in place with a screw for a hold that’s strong enough to handle the high speeds of a CNC machine. They have a negative rake, which means they have cutting edges on both sides. They last longer than comparable positive-rake inserts. As each edge dulls, you can rotate to a fresh one. When all the edges on one side are worn, flip the insert over. Built-in chip breakers prevent long chips from forming, so they won’t block the flow of coolant or damage your tool. Inserts sold individually come packed in a clear plastic case to protect cutting edges during shipment. Inserts sold in packs come factory sealed from the manufacturer for maximum traceability.