Dutch to English Tech/Engineering Manufacturing Flagpole accessories

I have hunted around on various websites trying to come up with an English solution. The link gives a picture of what this is. Basically, it's a little attachment to ensure that a diagonal flag hangs down straight (if attached to a wall) and prevents the flag from wrapping itself around the pole. All thoughts very welcome.

www.vlaggen.com/prijslijst_vlaggenstokken.php?main=4&sub=1