mining rock bolts 1.diameter:16-25mm 2.used for in mines,tunnel ... ,BV.professional factory 4.low price, good quality mining rock bolts(grooved bolt)1.Diameter:16mm,18mm,20mm,22mm,25mm2.used ... plate, 120mm,150mm,200mm,250mm,300mm square. thickness, 4mm,5mm,6mm,8mm,10mm, and so on.