Apparatus for producing uniform velocity distribution of fluids in conduits using a non-homogeneous resistance element. A system is described using a non-homogeneous resistance element together with, in the preferred embodiment, a homogeneous resistance element or a second non-homogeneous resistance element to obtain a uniform velocity distribution of fluids flowing in a conduit. The non-homogeneous resistance element is made up of a plurality of flow channels in the form of a honeycomb, with this honeycomb divided into various regions or zones where flow adjustment is desired in order to achieve the uniform velocity distribution. Specific control within these regions or zones is accomplished by inserting resistance units in the flow channels with the units of highest resistance value being inserted in those regions where the velocity is to be reduced the greatest. The resistance units can be inserted or removed after installation of the elements in a conduit to correct for any non-uniformity of velocity distribution that may occur. Disclosed are preferred methods of fabricating the homogeneous and non-homogeneous resistance elements, and the resistance units.