Xiamen ProDrill Equipment Co., Ltd
The 11 degree drill rods material is 23CrNiMoVA which is better than Z708 and 55SiMnMo.This material heat treatment is full carburization to improve the drill rods hardness and life. Last year, we have delivered the 23CrNiMoVA drill rods ( until now more than 2000pcs) to Peru, Russia and Ecuador gold mines. The feedback from different customers is well. In Peru gold, in the same gold mine, 23CrNi drill rods can drill 390meters while the Z708 rods can drill 170meters.The length from 0.5m to 5 meters is available. Now 1,830mm is in stock. Regards of the tapered drill bits, we recommend 32mm ( with 5 carbides) and 34mm ( with 6 carbides) , because these two types bits are right for hard rock such as granite, basalt and so on.