HOLD ON BLACK,
Check out this thread and look at my posts on pg 4 and 5 when your done. Ask me the questions you want to ask if you want to ask any.
http://www.reefcentral.com/forums/showthread.php?t=1952442
Tends to be U-channel aluminum, if you read the thread i posted above there is a whole discussion about it, go to page 5 and read my posts. and the answeres