I ordered 2 lights and get well. Have connected the staircase according to two lamps. One works and the other does not! Now it goes in search why? Error then I found a Verbindundsleitung between the LED railways was unsoldered! I then brought my soldering and soldered Verbindundsleitung. Yes it is lit. Something is unlikely to happen !!! Lamp without large claims -> ok For stairwell brightness is quite ok. Only require the lamp is to be recommended. The quality and output control of the manufacturer allows for doubt! Whether now or guarantee exists ?? Life I can not judge.