Tubes with MicroGroove technology can be made with copper or aluminium. Daniels' recordings cover the period of transition from 78-rpm to the dawn of microgroove recording. One purpose of Microgroove rifling was to increase the speed of producing rifle barrels. His success led to his nickname as "empereur du microsillon" (king of microgroove). Another example of M/S stereo is the stereophonic microgroove record. With MicroGroove technology, heat transfer is enhanced by grooving the inside surface of the tube.