These anatomical heart and brain necklaces are made from the same US coin. We engrave the detailed lines of the heart and the brain, then we carefully cut each half so they fit together perfectly. Two 20" thin chains will be sent with this order. However, if you would like different sizes offered below please message us immediately after ordering. We offer various chain sizes from: 18" thin 20" thin 24" thin 20" thick 24" thick Key Chain Adj Black Cord