Chrome plated hub cap measures 1 3/8" diameter. Link Chain measures 15" with an added 4" chain extender, with high quality lobster claw clasp. If you wish to wear this necklace longer with crest slightly into cleavage, there will be enough chain to do so. If you want to wear the chain shorter, you will not need to use the chain extender, rather the small amount of extra chain will hang down a little on your back giving it an extra sexy and appealing look. At the end of the chain extender is a stylish Retro-a-go-go! key measuring 7/8".