Detailed Serotonin Chemical Structure necklace pendant. I focused the design around the double lines to represent the double bonds between the atoms. This helps to make this pendant stand out from the rest. This is the perfect gift for any chemistry enthusiasts. The pendant will look best in any silver material. It feels sturdy and durable but elegant at the same time. This piece does NOT include the chain, but your local jewellery store will sell necklace chains with two clasps. If you have any feedback on this item please don't hesitate to contact me.