Usually called high-shear mixers, are the most common form of Dispersing Homogenising Emulsifying mixer. By placing a form of closely-fitting shroud around a high speed impeller, it is possible to create a shearing action between the blades and stator shroud. As material is centrifugally pumped through the mixing head, some of it will see this high shear zone and experience shear stressing that results in dispersive mixing. Where small or uniform dispersion are required, material must be cycled through the head many times to ensure statistically that all of the material has passed through the high shear zone at least once.