A retrofit kit for an existing light, that has a prewired assembly, including a housing having wiring to electrical mains, an LED light source, at least one control for said LED light source, both said LED light source and said control being wired to said wiring, and said housing having a at least one mounting device that fits on existing structure of the existing light. The mounting structure can include tabs, for example, that attach to hanging part of the light, or can include a part that attaches to the existing surfaces on the housing of the light that previously held the socket for the existing bulb.