... used in tunnling , mining support 4.Low price and high quality Hollow drill rock anchor, matched with good fittings, is ... out.4 Grouting pressure can be kept at a high level under the help of grouting stopper, so ... and the fractured rock is improved.5 With the high-strength coupling elongated by mechanical cutting technology, this ... *6mm,150*150*6mm,150*150*8mm. high strength hollow drill rock anchor