I got the Sun-Sun HW-304B.
I have read that the skimmers are useless and just won't work.
I see how people were saying that because when you fill your tank all the way up the skimmer would slide off and float around the tank making it useless.
What I did was raised the Curvy pipe so it would sit higher so that the skimmer wouldn't be so deep in the water and now it works great.
Here are some pics