... well drilling or oil well drilling2,Model: various kinds and according to the requirements of customers3,Material: ally steel, tungsten carbide insert4,Color: can ... HA) not sealed(W)11,Formation: soft formation, soft to medium hard formation, medium hard formation ,hard formation,very ... term: L/C at sight,T/T15,Delivery time:about two weeks,but still depending on the quantity of the order16,Advantage: ...