An impeller designed for higher viscosity products. A helix is shaped like a spiral, usually rotating close to the tank wall. The Flights of the helical shaped blades move the product up (or down) the tank wall, promoting top-to-bottom motion in viscous materials that is superior to simple anchor or "picket-fence" impellers. Helix impellers are specifically designed to fit the particular process. One, two or more helix flights; with or without lower "tank-bottom" blades; with either all-welded or bolted assemblies with adjustable blades. An internal screw (auger) may be added to the shaft to aid in material turnover.