The adjustable slide clasp is a small circular bead with a silicon inner. The silicon inner within the clasp grips the two ends of the 1mm cord when threaded through in opposite directions.
We use a flexible beading needle for the second cord to make it much easier to thread through the adjustable slide clasp. Once through the hole all you have to do is pull the two ends of the thread away from each other to tighten the necklace or bracelet.
To loosen grab a hold of the bead and pull away from the neck or wrist or pull the cord ends apart.