MADE FROM HIGH-SPEED STEEL AND 5% COBALT: improve much higher heat resistance because of cobalt steel's high red hardness, provide strong durable performance compared to typical hss drill bits. CAN BE REPEATEDLY SHARPENED AS NEEDED: cobalt drill bit's hardness is uniform throughout the entire material, so that can be repeatedly sharpened without damaging the cutting edge allowing it to drill more than hss drill bits.
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