Abstract: The present invention describes a low frequency, low shear, in-line mixer which operates using a pressurized flow of material, in gas or liquid form, to efficiently mix the flow with another gas, liquid or solid (small, particle-sized) material. The essential components are a chamber, an inlet orifice and a tapered, cantilevered reed with a weight on the unattached end of the reed. The pressurized flow of material across the cantilevered reed induces it to vibrate, thereby mixing the materials in the pressurized flow. Mathematical formulae are used in setting the construction parameters for the reed so that it vibrates at a lower frequency, creates less shear and consumes less power than previous mixers of similar design.