A recessed lighting unit for mounting to a ceiling or a wall is provided. The recessed lighting unit includes an interface module having a through-duct. The through-duct may be coupled to a wire connector assembly to secure an electrical wire to the interface module and allow the electrical wire to reach a light source module. The wire connector assembly may be twisted and locked to the interface module without the use of tools. The lighting trim may be snapped on to an interface module through the use of a flexible retainer ring. The lighting trim may also be twisted and locked to an interface module without the use of tools. The present invention provides for a reduced set of components while ensuring adaptability and easy installation of lighting units. Other embodiments are also described and claimed.