I've found the elastic straps in the ST1300 topbox to be very handy for stabilising the load, especially when it mounts up over the bottom half and wants to fall out to the left when you open the lid.
That's all fine, except the trick of remembering how those nifty red plastic thingamybobs link up. It's not intuitive. I know- just don't have them twisted. That's fine but my way is easier.
I've cheated and written UP on the two so I can immediately get them to neatly link.