This set of 100 black polyester necklace cords with lobster clasps are approximately 17"L with a 2mm diameter, and the total length is 19.25". The extension chain is 2.25", and can be adjusted freely. Made of polyester fiber with a wax alloy finish. The polyester necklace cord is light weight and attached with silvertone zinc metal. Great for DIY jewelry making projects or for multiple necklace pendants. The design is smooth and flexible for comfort and and ease of use. You can add a pendant or other piece of jewelry and make it a special necklace for you and all your friends. Great for both women and men. You receive a total of 100 waxed polyester cord necklaces.