Most geometries fall into three simple categories. You have finishing, medium and roughing. Finishing geometries, like our PF designation, are designed for light cuts, running at lower feeds and small depths of cut. They have sharp edges and their aim is to give you the best surface finish that that insert can deliver. Then we have medium geometries, which is like our PM. These are more versatile, they handle a wider range of conditions. And then finally we have roughing geometries, like our PR designation. These are designed for strength, so they want to run at higher feeds, heavier cuts and more heavily honed edges to survive the load that these increased forces create. But here's the key thing. When you pick one of these, you're not just picking a chip breaker shape, you're picking a package. A PF gives you a finishing chip breaker and a sharp edge, because that's what light cuts need. A PR gives you an aggressive chip breaker and a honed edge, because heavy cuts demand both. The manufacturer has already matched them for you. And if you get this wrong, you'll feel it quickly. Put a PF into a roughing cut and that sharp, delicate edge will chip or fracture under load pretty quick. The chip breaker just isn't built to handle that much material and that much force. So you'll see poor chip control and a very short tool life. But if you go the other way, and you use a PR in a light finishing cut, then the insert will rub instead of giving a clean cut, and you'll get a poor surface finish. You'll get more heat build up in the part. So rather than picking based on preferences, it's about matching the geometry to the type of cut you're making. And we can look at this in more detail now.