The propagator is a Stewart, just a basic non-thermostat 22W heated through the base - it's missing the handles, has been melted slightly (oops one of the hot components on the light touched it!
The light is actually an Enfis light engine which is basically an array of LED packed together with a heatsink attached to the back and integrated PSU/dimmer control by USB. More info here:
http://docs-europe.electrocomponents.com/webdocs/0913/0900766b8091353d.pdf
The model I selected is the 465nm (+/-20) which corresponds to the Chlorophyll maximum absorption wavelength for vegetative growth. Chlorophyll fluoresces at something like 467 so that why the leaves have some florescent appearance too.
Chlorophyll A has peaks at 430 and 662.
Chlorophyll B has peaks at 453 and 642.
Normal light power (watts) corresponds to the area under the spectra over a wide range over wave lengths - usually a couple of hundred nanometres. Lumens are based on the human eye sensitivity which looks like a bell distribution curve so you may have high lumen but low power output at a specific wavelength.
The engine at max pushes 5750mW which doesn't sound like much but given that the output is a narrow band (40nm in total) with it's peak at 465nm the efficiency in terms of power-to-light is higher than the ~6 watts indicates. I wear sunglasses to cut down the glare when working near it (and it's on minimum power!). So basically it's the same idea of a laser to provide a narrow wavelength band to maximise light output for the power. Power is 38W max.. brightness and monitoring via USB
Still it's not quite the same as a 400W bulb pushing out 55,000 lumen which would require a goof 3 feet between and the top of the plants!
The temps inside range from 26-32 depending on how much I cover with the towel.
Below is a pic of a few from last year. We just have a small make shift 'glasshouse' in the garden made from old double glazing panes 
