I recently bought these to use for my 10'6", 31" wide SUP board.
First thing I noticed was the the plastic construction seemed a little light, compared to the quality of Yakima products I am more used to.
I mounted these on my Yakima bar rack, which went on easily. But I worry that they would be pretty easy to steal.
I then tried to load the board onto the rack cradles, but they didn't fit the boards rails well. The worse was trying to clip the strap onto the rack and across the board. They advertise the racks as being able to hold 2 boards; I couldn't even get it to cross and hold down my board securely! The strap needs to be at least a foot longer to be useable and be able to be cinched down properly. Also, the plastic clips that attach the strap to the rack seem pretty flimsy.
These might work for shortboards, but don't see how you could be even more then 1 longboard on it.
Returning the racks.