There was only a problem because an LED was mechanically damaged. The seller but quickly responded to my email and sent replacement. The return of beschätigten LED was free for the buyer. -> Exemplary!
Then I had a little problem with the version of my desk lamp. The inclusion of the two legs is recessed and halogen lamps are narrower so that they also find their place there. This problem I have but simply solved by I extended both legs with 1mm thick wire (easily soldered) and also worked as expected.
The power I have a laboratory power supply checked times and I can confirm the 4W. Increases or decreases the power consumption so that always the same performance is also used at a slightly lower or higher voltage.
I would buy this lamp again.