Value packs for filigree dread/braid cuffs come in packages of 50 and measure about 10 mm 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.
Size: 10mm x 8mm.
Brand: I Kick Shins.
Color: Silver filigree or Gold crowns.