High-quality glass Fresnel lenses were used in lighthouses, where they were considered state of the art in the late 19th and through the middle of the 20th centuries; most lighthouses have now retired glass Fresnel lenses from service and replaced them with much less expensive and more durable aerobeacons, which themselves often contain plastic Fresnel lenses. Lighthouse Fresnel lens systems typically include extra annular prismatic elements, arrayed in faceted domes above and below the central planar Fresnel, in order to catch all light emitted from the light source. The light path through these elements can include an internal reflection, rather than the simple refraction in the planar Fresnel element. These lenses conferred many practical benefits upon the designers, builders, and users of lighthouses and their illumination. Among other things, smaller lenses could fit into more compact spaces. Greater light transmission over longer distances, and varied patterns, made it possible to triangulate a position.