It's a thing of beauty installed. Stainless steel Allen-head bolts are used as fasteners and the cover has a rubber O-ring type gasket. Note how we routed the wires up along the brake lines. Our truck has the load-type brake proportioning valve, which we found would not directly attach to its original location. We used that as an excuse to simply eliminate the non-op unit anyway. To retain it would require some adaptation to the mounting brackets.