It depends what you want it for...
I bought the standard one the stretches between the roof and the floor. They suck. It will keep the dog back there when parked, or cruising down the highway, but that's about it. I wanted something that would contain my dogs in the event of an accident. a 65lbs and 90lbs flying object in a roll over would not be fun. I recall looking into an actual barrier from Oz. It was rock solid. Bolted in. And was very expensive if I recall correctly. I can't remember the name of it.
I am back to using dog crates strapped to the floor.