Affinity

While wearing this ring, you are invigorated with elemental energy. When casting a spell that does the damage type of your Draconic Bloodline, you can choose to do 1d4 extra. In addition, you are able to channel more than one kind of elemental power through your draconic bloodline.  Every long rest, choose 1 element. This element may also be used for your 6th level class feature Elemental Affinity. in addition to your element, but not replacing it.

For reference:

Elemental Affinity

Starting at 6th level, when you cast a spell that deals damage of the type associated with your draconic ancestry, you can add your Charisma modifier to one damage roll of that spell. At the same time, you can spend 1 sorcery point to gain resistance to that damage type for 1 hour.

Notes: Damage: Lightning, Sorcerer, Draconic Bloodline