A 5" aperture specification grade modular housing platform that offers a accepts a variety of modules utilizing compact fluorescent, low voltage and line voltage tungsten-halogen lamps. Suitable for 2x10 residential framing or commercial installation. The platform is airtight to prevent energy loss, room drafts, dust marks on ceilings and reduce sound transmission. Insulation must be kept 3" from fixtures sides and top. A complete fixture requires three components: a PN5 housing platform, a lamp module and a 5" optical element. Elements and modules may be changed after installation to provide a variety of distributions.