The connectors (9x3mm) are in bronze colored metal. They are to "clip" (you have to insert the small ball) on the end of a ball chain 2 to 2.5mm in diameter. Check if this size suits you! This connector allows you to extend your chain or close it permanently. Essential primer for finishing your ball chain creations! - If you buy more than one item, don't forget to tell me ask for the total BEFORE paying by ebay messaging or email, because the reduction in shipping costs does not happen automatically, And ebay shopping cart not working well. Items are carefully packaged in bags, bubble wrap if necessary, and taped in the envelope. Every order is important, small or large. My dear customers from Europe and around the world, if you want a tracked shipment, please ask me by email, I will send.