Make an overhand knot at one end of the cord, then pull tight to secure.
Make another overhand knot next to the first knot. Before pulling the second knot tight, thread the end of the cord labelled A back up through the second knot, as shown.
Slide the second knot along the cord so it’s positioned next to the first knot, then pull the end of the cord labelled A through the second knot to tighten. This enables you to open and close the knot.