These bird skulls are solid sterling silver. The silver has been blackened and then polished back to highlight the details. Each one is approximately 30mm long. The cufflink attachments are the easy and secure swivel back style. They have been stamped with a '925' stamp to guarantee the metals silver content, as well as my own makers mark (WLG). They are handmade in my studio in Melbourne, and come packaged in a beautiful black box. All our shipping is FREE of charge.