An enclosure which acts as a heat sink for dissipating heat generated by electronic components within the housing. The outer surface of the enclosure includes numerous cooling fins, preferably on all six faces of the enclosure, to help dissipate heat. The fins are diagonally oriented, rather than vertical or horizontal, to permit them to be effective whether the unit is mounted horizontally or vertically. In addition to dissipating heat, the enclosure is rain tight, EMI-tight and ESD-tight. The inside major surfaces of the enclosure include a number of pins extending inwardly to help increase the surface area for heat transfer into the enclosure material. The pins extend deeply into the interior of the enclosure, and are made shorter only where necessary to avoid large components on the printed circuit card. The spaces between the pins allow convection of the heated air whether the enclosure is vertically or horizontally mounted. The fins and pins together maximize heat dissipation from the electronics within the enclosure regardless of whether the enclosure is vertically or horizontally mounted.