20x3cm rain light.  12v 9w LED.  Easy to mount with a single hole required. 

LIke all similar products, these arrive without connectors, but if you're not handy with a soldering iron, choose an option to have connectors of your choice soldered on before delivery.  Note, the mounting hole is too small to pass a multi-pole block connector through, so the options are bullet or blade connectors.  Male on positive, female on negative to make sure that even in a hurry it won't get wired up the wrong way round.