There are three dragons primarily represented in Norse mythology, Nidhogg (or Nidhoggr), Jormungand (or Jormungandr), and Fafnir.
Nidhogg, according to the Voluspa, is a dragon that lives under the roots of Yggdrasil (the world tree that connects the nine worlds of Norse mythology) and eats the corpses of the dead.
This Ring looks like dragon claws clamping down.
This ring is adjustable and will fit most fingers, but bending it repeatedly can weaken the metal. It is recommended to only bend it one time to adjust the fit to the finger you've chosen and not to bend it again to suit another finger as repeated strain will weaken the metal.