If you want to use your own thread to make a phone strap, then this is what you need. The cap is the metal end seen on phone strap. See picture of a full phone strap on the right (also sold on this website) and of the cap alone on the left. There is also a close-up picture of the cap (top-left). The cap has a hole for the split ring. Knot the thread of your choice inside. Size: 8mm long, 5mm diameter.