Our home has been fitted with fairly common / standard Superlux SD100 downlights (http://www.superlux.co.nz/products/?id=343&product=244) which take a R80 light bulb, but I notice that there is a screw thread on the opening that sits flush with the ceiling -- anyone know what this is for? The website doesn't really explain it but it must be for something.

I am hoping that you can maybe buy some sort of screw-in insert that allows you to put a 'normal' size bulb in there (instead of the R80) without you then seeing the innards of the downlighter unit. I really want to replace the bulbs throughout with LEDs but R80 LEDs are few and far between.