The unit supports filters, has a replaceable bulb, is sturdy and submersible. Given the light output, the battery life is phenomenal. The only thing to watch out for is the O-ring. After replacing the batteries, make sure the o-ring doesn't get popped out of its groove, or else it won't be sealed properly. Minor problem that can only occur when changing the batteries.
Pros: Submersible, very bright, long-lasting if you consider the output
Cons: O-ring can get snagged, when replacing batteries, compromising water tightness
This review was written in the old system and had content requirements that are different than reviews written today.