Abstract: A mirror assembly for external use on large trucks, tractors, buses, etc. A first reflective surface is pivotably supported with respect to a large, shell-like housing in such a way that the surface is movable at will about two perpendicular axes. A powered hydraulic means is used for selectively rotating the reflective surface to a desired position and normally holding it in a static mode. The hydraulic means includes reservoirs in communication with two hydraulic cylinders, and a plurality of check valves arranged in sets and interposed between the reservoirs and the chambers in the cylinders. The hydraulic fluid is chosen from the group that comprises engine oil, power steering fluid, transmission oil and ethylene glycol.