The adjustable slide clasp is a small circular bead with a silicon lining that grips the two ends of the thread when pushed through silicon hole from opposite sides.
This adjustable sliding clasp accommodates 2mm cord.
We used a flexible beading needle to get the second cord through the hole.
Once through the hole you just pull the two ends of the thread away from each other to tighten the necklace/bracelet. To loosen just grab a hold of the bead and pull away from the neck or wrist.