The Isis Rack features bottom "Cone Foot Terminators" made of solid aircraft aluminum for optimal interface to any floor. The leveling spikes are reversible; one side is flat, for optimal coupling to flat surfaces, and the other is sharpened for use on carpeted areas, or when used as recommended with a set of Precision Coupler bases (included with Isis Rack shelves).
Here, at the critical interface between rack structure and the floor (the mechanical "ground" connection), either aluminum or copper will give better sonic results because of the superior transmission characteristics of these metals. We chose not to use stainless steel points for rack leveling spikes in the Isis, since we have found that they are bettered sonically at this critical interface point by "faster" metals. While aircraft aluminum spikes would be better than brass, steel or stainless steel at this particular point, we take extra time and care to custom make Tellurium copper reversible leveling spikes. Tellurium copper has even better transmission speed than aluminum (the only metal with more efficient energy transmission than aluminum and copper is silver).