Depth Stop Collar Drill Bit Ring 3,4,5,6,8,10,12,16mm Positioner Collars Locator. 【Inner hole】: 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 16mm. There is a top screw on the side of the limit ring to fasten the shaft, which can firmly fix the DIY accessory.
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