- You may be looking for Air Charm, a device with a similar function.
The Air Necklace is a device used by various Mobians for different purposes.
After shattering the Master Emerald to keep it out of Dr. Eggman's hands Knuckles the Echidna used an Air Necklace in the Aquatic Mine Zone to help him breath underwater while looking for the shards. (SA2)
- The Air Necklace was introduced in the game Sonic Adventure 2.