Carbide Cutter Three Blade Counter Sink by Yu Xuanjie 1.00" / 25.4mm with .3185" / 10mm HoleYu Xuanjie Tools
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Will Fit a 3/8" Short Drill +/- a few Thousandths or 10mm +/-
Can be used independently to face without a drill bit.
Use shim stock wrapped around to secure drill bits smaller than 10mm.