3.175 – 6mm HSS Ground End Mill Cutter 1 Flute PCB Engraving Bit CNC Router Tool. Tungsten steel material: high hardness, high wear resistance, sharp edge, not easy to break. Universal rounded handle, chamfered design, tightening without slipping, more efficient operation. Fine cutting, high processing accuracy, sharp and non-stick, good cutting effect. Sharp cutting, no burr. Applicable machines: engraving machine, CNC, PCP. Wide range of materials that can be engraved, including: circuit boards, Bakelite, epoxy boards, gold, silver, copper and iron and other metal-type processing. Specification Description: Blade Diameter x Blade Length x Overall Length (select your size from the drop down menu above). Shank diameter: 3.175mm/ 4mm / 6mm. Overall length: 38mm / 40mm/ 50mm/ 55mm/ 70mm/ 80mm. Multiple models to choose from. Choose your size from the drop down menu above.