Special grinding technology, alloy bit-blade alloy, combined with inner, middle and outer three edges and front and rear inclination angle design, low cutting resistance and high hole opening efficiency. Center positioning, precise drilling-grinding center positioning drill, positioning before drilling, equipped with discharging spring to accurate, fast and stable cutting of drilling. Optimize the design of the chip removal groove to smooth chip removal - adopt a -new upgraded chip removal groove, supplemented by a special chip removal hole, so as to smooth chip removal and effectively prevent edge collapse due to chip blockage. Non-slip triangular handle, clamping and fastening - triangular handle type, clamping is more firm, and it is not easy to slip, making the opening and more reliable. Suitable for stainless steel, cast iron, aluminum alloy and non-standard metals. Name:hole opener set Quantity:6pcs/set Pay attention to 1. For specifications of 70mm and below, a chuck with a handle of more than 10mm can be used, for specifications of 70mm and above, a chuck with a handle of more than 13mm can be used. 2. The feed is smooth, the workpiece is compacted, and the rotating speed should not be too fast. 3. Open the hole and add water Colour:Silver Material:alloy Package Contents: 1 * hole opener set Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.