A UFO LED high bay light is a UFO disc-shaped LED luminaire system which features a flat integral aluminum housing with optics specifically configured to optimize the light distribution over a given area without relying on bulky reflectors. LEDs are directional in nature and require optics, which is usually reflectors for conventional LED high bay lights, in order to meet the light output patterns necessary for many applications. However, conventional fixtures typically mimic traditional metal-halide (MH) fixtures in luminaire shape and furthermore designed with bulky and heavy heat sinks. The entire fixture not only looks outdated and clumsy, but also does not match well with contemporary architectural design. Moreover, the large volumes of thin aluminum reflectors need to be packed separately with extra caution during transportation, which further adds to the delivery cost. UFO LED high bay lights are more compact and efficient than the traditional LED fixtures. They look better, last longer, and are easier to transport and install.