To maintain optimal performace, D.W. Fearn/Hazelrigg Industries have always recommended that you provide at least one rack unit (RU) of space above and below their products. The Hazelrigg Industries VPH, a 1.75 inch (1RU) ventilated rack panel that is painted with the same powder coat paint used on all Hazelrigg Industries products. The rack panel has a Hazelrigg Industries logo and vacuum tube icon in the same silver that used on their other products. These panels are made of .125 inch laser-cut aluminum.