A reflector is a device designed to reroute the flux (illuminance) from a source by the process of reflection. The reflector is placed between the light source and the housing. It's the primary optical component of the luminaire. LED reflectors are constructed from high reflectivity materials that are engineered to maximize light output by directing the light emitted from an LED light source. The majority of luminaires are made with pre-painted steel. Some luminaire manufacturers typically use white powder coated steel. Reflectors are usually available in powder coated aluminum. White reflectors are the best choice at mounting heights of 4m (13 ft.) or less. Besides the fact that white powder coat is more reflective, white powder coat has other positive aspects; it is more environmentally friendly when employed on the metal, and it holds up to cleaning and the reflectivity is well maintained eventually. Enhanced aluminum reflectors are usually a more sensible choice for high mounting heights attributable to increased optical control. Basic aluminum should not even be considered because of its lower reflectance. A refractor is used to redirect the flux from a source, typically by the process of refraction. A baffle is a single opaque or translucent element to shield a source from direct view at certain angles, to absorb or block unwanted light, as well as to reflect and redirect light. A louver (or louver grid) is a series of baffles designed to shield a source from view at certain angles, to absorb or block unwanted light, or to reflect and redirect light. The baffles are frequently arranged in a geometric pattern. Polycarbonate (PC) can be used as a reflector by adding light-reflecting pigments to the material. This produces a product that reflects light diffusely. PC reflectors can be more cost effective than metal reflectors, which frequently require expensive, time-consuming processes such as vacuum coating or wet-chemical electroplating.