Saw those but they looked like they were for lifted trucks? Plus they are pretty rich compared to the old Ride Rites! Apples and pickles, I know. I dont expect to need 12" of travel!
They are intended for low lift, like stock-2" rear lift sort of thing. They are decent but extremely pricy. And, they are not the best option for heavy loads. They are ok for a 1000lbs in the box or whatever. But if your really loading your truck up say 4000lbs, other shorter air bags will be far superior for stability.