... , mining support 4.Low price and high quality Hollow drill rock anchor, matched with good fittings, is made of seamless ... wave-shape thread, this anchor can be used to drill holes with help of bit.3 It is used as ... take the measure of sleeve protecting and pregrouting to drill the holes in condition of various surrounding rocks since ... 150*150*6mm,150*150*8mm. high strength hollow drill rock anchor