12 1/4" inch 311mm drag bit/pdc drag drill bit for water well drilling 1.ISO9001:2000 2.Wings/Blade: 3, 4 ABOUT ... formation f≤6, like mudstone, shale, sandstone, etc. mainly used for drain hole, grouting hole, geological and hydrology drilling, Usually drag ... polycrystalline diamond layer sintered with tungsten carbide substrates. 12 1/4" inch 311mm drag bit/pdc drag drill bit for water well drilling