These are designed to have a knotted rope permanently attached on the back side of them, which gets run around a bar (or whatever you need to tie down), and then through the hole in the bottom, with the teeth holding the rope in place.
The rope used is cotton-thread 3/8". We use these to do everything from cinching up coffee bags, to holding down film gear and bounce boards.
DISCLAIMER Don't use this for climbing or anything life threatening. It will break and I don't want anything bad to happen to anyone :)