... rock bolts 1.diameter:16-25mm 2.used for in mines,tunnel 3.ISO,SGS,BV.professional factory 4 ... )1.Diameter:16mm,18mm,20mm,22mm,25mm2.used for in mines,tunnel3.ISO,SGS,BV4. low price, good ... end is rolled thread. this bolt has been approved in Gold Mines of Elorado China.1,Features:1. Grooved ... .4. fast andeasy installation by mechanized tools5. available in black or hot dip galvanized.6. length as your ...