Matched back-to-back tapered roller bearings are the most popular double row tapered bearing design. They carry heavy radial and axial loads and axial forces in both directions. They are manufactured together as a set that includes two tapered roller bearings, and a precision machined set of shims. An essential feature of this configuration is that when the shaft thermally expands lengthwise, the axial preload forces decrease in the bearing. It will run at a lower temperature than a face-to-face bearing in the same situation. It is much easier to use in industrial settings where operating temperatures vary significantly.