12" inch 305mm drag bit/pdc drag drill bit for water well drilling 1.ISO9001:2000 ... , like mudstone, shale, sandstone, etc. mainly used for drain hole, grouting hole, geological and hydrology drilling, ... over.3. Fast penetrating two wing drill bit for wet drilling with centre flushing.4. PDC ... sintered with tungsten carbide substrates. 12" inch 305mm drag bit/pdc drag drill bit for water well drilling