Drag reducing agents can be broadly classified  under the following four categories – Polymers, Solid-particle suspensions, Biological additives, and Surfactants.  These agents are made out of high molecular weight polymers or micellar systems. The polymers help with drag reduction by decreasing turbulence in the oil lines. This allows for oil to be pumped through at lower pressures, saving energy and money. Although these drag reducing agents are mostly used in oil lines, there is research being done to see how helpful polymers could be in reducing drag in veins and arteries.