Permanent Symmetric Casing System by DTH Hammer Details Link : https://www.alibaba.com/product-detail/Professional-SOD-114-Retrievable-Overburden-Drill_62367074403.html?spm=a2747.manage.0.0.74c371d2cAQT7X Advantages：  Full face head designed for faster penetration and straighter hole  Less torque is required  Can drill in vertical, horizontal or any direction  Minimize disruption to the drilled hole  Varied ring bit diameters to suit different casing requirement #SymmetricCasing #DTHHammer #overburdensystem #flexible #efficient #rocktools #prodrill https://www.instagram.com/p/B-yybuSj_Y9/?igshid=x5t7zyw8i60u