Help with my new (second hand tank)

[Salts155R]

So after a day of building a frame yesterday I’ve finally got my trigon 350 that was given to me in place.
Everything was left outside for months whilst they moved house and had no room for it.
I want to replace the the bulbs with led ones which I have found online but there’s a smaller light at the back that I can’t find any info on.
it was previously used for turtles if that helps anyone