A club face machined flat by a CNC mill from a solid block of metal rather than cast in a mold. Milling matters because casting can leave tiny high and low spots; a milled face is precisely flat, so the ball comes off the same way every time — critical on putters, where Scotty Cameron built a brand on it. The fine circular milling marks also soften feel slightly and, on putters, help the ball start rolling sooner instead of skidding. On wedges, milled faces and grooves deliver more consistent spin. Trade-off: milling is slower and pricier than casting, hence the premium price tags.