The Air Necklace consists of a grey necklace-styled oxygen bottle shaped like a handle and the name "Air Necklace" written on it.
The Air Necklace was invented by Rotor Walrus for Knuckles to make up for his lack of special abilities after he lost them. When Sonic and Knuckles were about engage Hunter, Sonic left the Air Necklace behind, preferred to travel "light". The Air Necklace would be fully abandoned when Knuckles regained his lost powers.
- The Air Necklace is based on the Level Up Item that appeared in Sonic Adventure 2 and Sonic Adventure 2: Battle.
- ↑ 1.0 1.1 1.2 Sonic the Hedgehog #140, "Return to Angel Island Part 3: How Many Echidnas Does It Take to Protect a Master Emerald?"
- ↑ Sonic the Hedgehog #138, "Return to Angel Island Part 1: The Message"
- ↑ Sonic the Hedgehog #139, "Return to Angel Island Part 2: Avatar"
- ↑ Sonic the Hedgehog #141, "Return to Angel Island Part 4: Ultimate Hero"