The disclosed lateral transfer retroreflectors include three flat reflectors, two of them being united at right angles to form a hollow roof reflector, and a third being carried on a central member at the required offset distance from the roof reflector and in a plane perpendicular to each of the first two reflectors. The parts are related to each other in two embodiments which enable adjustment of the planes of the flat reflectors relative to each other without exacting requirements as to right-angled edges of any of the flat reflectors or as to parallelism of end faces of the central member.