

So the upper one uses the 2 grimloc fastened to the top side rail of the rack, and the velcro lower strap fastens to the upright and stop it flapping.
The lower one is the other bag that uses a grimloc to fasten to the upright to stop it flapping the the strap loops over the rack to hold it on, using a strap defender I think it's called to hold rest of strap tight.

