Drill-Its Griffin PCD bits are our cutting edge design of Polycrystalline Diamond tools, they are built to last and tackle the hardest formations a job can throw at you. The inserts are made from the highest quality materials to ensure maximum efficiency from a long lasting bit. The Griffin set of drill bits are our range of Set To Liner PCD models, meaning the casing string that does not extend to the top of the wellbore, but instead is anchored or suspended from inside the bottom of the previous casing string. There is no difference between the casing joints themselves.