These units are drop in replacements for existing Aquience light units. The sealed nature of these means that once broken they cannot be repaired and must be replaced.
If your set up is an earlier one then it might well have come with a T8 light unit accepting 1" diameter tubes. These have now been replaced by the brighter T5 units which will fit your setup but will not accept your old T8 tubes.
If you require more information please do get in touch. No one knows more about Aqua One products that Aquarium Parts.
* Need other lighting spares or accessories for Aqua One? See all Aqua One Lighting