These professional-grade cutters will totally drill-out spot welds, with little or no grinding required to finish the job. Make fast, clean cuts without cutting into the bottom skin. This solid one-piece cutter is machined from M2 tool steel. The self-centering point prevents “drill walking”. Extremely durable and long-lasting – shop-tested at over 300 cuts without re-sharpening. The 3/8″ diameter cutter applies to most applications; the 1/2″ diameter cutter is especially needed for trucks and convertibles. Drill at 700 – 2,000 RPM.