Roof rack ladder (or other) "stops"...

[CyclistInMa]

Hi All...

I have the factory rack and crossbars. I got them so that I can occasionally cary some long lumber on the roof. On my old truck I had "stops" i.e. those things that make it easier to snug up and then tie down stuff. Any ideas if there is such a thing that would fit on the Mazda crossbars? Like these... http://rackwarehouse.com.p2.hostingprod.com/images/productimages/thule/t503-2.jpg

Ideally I would take them off when not needed as they will make a ton of noise...

Thanks!