Embodiments of the disclosure pertain to a downhole tool useable for isolating sections of a wellbore that includes a mandrel, the mandrel further having a body comprising an external surface, and an inner bore formed therein; a distal end; and a proximate end; wherein the mandrel is made of composite material, wherein a set of shear threads are disposed along a surface of the inner bore at the proximate end. Embodiments of the tool include a slip disposed about the mandrel, wherein the slip comprises a one-piece configuration.