At first glance you might think this is in the wrong section, that big black plastic base looking like something you'd expect to find on an early CFL...look a bit closer however and you'll find that this is actually something rather more unusual, and quite interesting.

When CFLs were in their infancy, a clever idea which was tried out (I believe Thorn were first off the mark with it) was to sell ballast units which plugged straight into a normal lamp holder with replaceable lamp units.  While these plug in retrofits didn't really last, the principle of the fixed ballast and disposable tubes did, and is used in a lot of new installations to date.  This however appears to be a similar idea to the old retrofit CFLs...but with a halogen incandescent flavour.

The resemblance of this lamp to a PAR38 reflector lamp is less than coincidental.  PAR38 lamps are horrendously expensive for what they are, even when bought in bulk.  This unit appears to have been designed to allow the same role to be filled by relatively cheap 12V MR16 halogen lamps without any need for alterations to the power supply or fixtures.  Simply screw this into the socket, clip the MR16 in place, and flick the switch.

Built into the black plastic case is a step down transformer (I assume - while there could be a switch mode supply in there, the apparent age, weight and power factor of the unit lead me to believe it's just a transformer), which steps down the 230V mains to the 12V required by the lamp.  This transformer is capable of powering lamps rated at up to 35W (clearly aimed at the 50W PAR38), though the text states quite clearly "Use 35 Watt lamp only" - it didn't seem to mind running with the 20W lamp which was fitted when I received it though.

It's a smart looking unit, the "reflector" being very shiny chrome plated plastic (getting rid of all the fingerprints for the photos was a nightmare!), and the detachable plastic front cover finishes the appearance off - especially when a dichroic lamp is used, when the pinkish light escaping through the reflector makes the whole thing light up quite impressively.

It's a clever idea, one which I've never encountered before, and I'd be most interested if anyone can shed further light on this piece of hardware, especially as to whether it was ever commercially available.