When I originally ordered these lights I didn't think about the piece I would need to actually get them power so make sure to purchase a power block or one with an adapter on it.They have linking capability so you can have several of them on one adapter. They are very bright but they can be hard to affix to your aquarium. The suggestion is to screw them to the lamp head but I've found double sided tape or a suction cup on the outside of the tank work really well.There really aren't any negatives to these lights. I would definitely purchase them again.