SCWD's are an inexpensive alternative to like an Ocean's Motion and some of the other current directors out there. They are relatively simple in construction, which means less stuff to break and are a great little addition if you are just looking to get some variance in water movement. The only real downside would be that they are not programmable. The water only comes out the left side, then right alternatively, so if you have 2 of them, it's only 1, 3 then 2, 4 rather than like the Ocean's Motion which can be 1, 3 & 2, 4 OR 1, 4, 2, 3 and other sequential patterns. All in all though, the SCWD's are good bang for buck.