An anklet sits where it is likely to be caught on things, so we make this one braided rather than a single strand: three cords twisted together survive abrasion far better than one, and if the outer strands wear the cord does not part.
The sliding knot is the same mechanism as on our red string bracelet — a loop that tightens by pulling two ends — and the bead sits over it to hide the join. Silk slides less than nylon, which is an advantage here because an anklet that loosens as you walk is worse than one that does not.
We do not describe the red cord as changing anything. It is a custom with a documented use, mostly around benmingnian years, and that is the whole of what we sell.