---Material : Quality Copper and Magnet, Reliable quality, stronger suction.---Package included: 10 sets---The hole inside diameter:3/4/5/6/7/8mm--Fit for 3/4/5/6/7/8mm cord---Open or close with twist the magnetic clasp. This is a perfect design, it can instead of ordinary rope knot, more solid, more durable, more convenient.---Applicable to a variety of material chains, such as: leather rope, pleather, silk, and, satin, cord, necklaces. In the hole of the button and the end of the rope, add a similar glue like DAB, and then insert the end of the rope with the same hole diameter into the hole until it is glued. Use for making leather cord. Bracelet, necklace and another DIY project.