Dread cuffs come in packs of 10 and measure about 8mm in diameter when they're completely closed. They're easily bendable, though, so you can squeeze them onto larger dreads if you leave a small gap in the back, or you can double up two at a time and make one really big cuff instead. These cuffs have ridges along the sides that make them look like corrugated tubing.
Size: 8mm x 16mm.
Brand: I Kick Shins.
In the third picture, Elizabeth is wearing a mix of hair beads and cuffs, including corrugated tube cuffs in Silver.