Diamond Cutter bit, Extra Fine (Diamond Nail Drill Bit) Ideal for Cuticle Care. Diamond bit produced from HIGH QUALITY stainless steel, coated with natural diamonds. Long product life and high performance. Bur is fitted with 3/32″(2.35mm) shaft, an industry standard for use in nail. Can be used with podiatry drills and portable drills. Recommended speed is from 12 000 to 30 000 rpm.