The 2-020 series housing is designed for non-insulated ceilings, allowing for installation of very shallow plenums, as low as 4". It’s sleek footprint allows for compatibility with most ceiling applications. Rated for non-insulated ceilings. Low voltage (12V) MR16 lamp (sold separately). Porcelin Bi Pin socket type GX5.3. MR16 LED lamp is compatible with E15 electronic transformer option.