As an important part of drill string, drill collar can supply the drill bit and increase the rigidity of drill string. Dril collar are manufactured strictly according to API Spec7-1 standard with material of AISI 4145 Mod. We supply slick drill collars, spiral drill collars, etc. The size of drill collar we can provide is from 3.1/8 to 11 inches. We can also provide other drill collars at customers’ specific request.