11 1/2" inch 292mm drag bit/pdc drag drill bit for water well drilling 1.ISO9001:2000 2.Wings/Blade: 3, 4 ABOUT USZhengzhou ... f≤6, like mudstone, shale, sandstone, etc. mainly used for drain hole, grouting hole, geological and hydrology drilling, Usually drag ... diamond layer sintered with tungsten carbide substrates. 11 1/2" inch 292mm drag bit/pdc drag drill bit for water well drilling