overflow box possiblity-need opinions...

I am converting a freshwater tank to a saltwater and need to add an overflow box to the system. What kind is great and what kind isn't based on experience? They all sound great on the boxes and their own websites but what really works out there. I found one possiblity "Tom Skimmer Box Auto Start and Stop," any thoughts would be great!!! Thanks so much!!!
From what i have heard about overflows do not get one that has a solid overflow section the tube ones seem to work good. If you would like to try a diy. there were some really good plans on here for overflows made out of pvc. i personally bought one with two overflow tubes and the biggest problem i have had is maybe once every two months i shut down the overflow to clean any growth but this can be prevented by trying to put some dark plastic over the top of it.