Special thread for tasbihs, sold as whole roll, 100% nylon, 12 plies that can fit into smaller than 1 mm holes, well suited to wood tasbihs.
Tasbih beads develop hairs on ordinary threads due to continuous drag that causes wear. As a result ordinary threads break after a relatively short period of use and the hairs developed on the thread lowers the collectible value of the tasbih. In Turkey these special threads are used: they don't become hairy, they are extremely resistant and durable. The thickness of the thread is commercially defined by the number of plies.