Hi all, just wondering if anyone knows the size of the o-ring that seals the Subtank Nano's airflow control to the rest of the tank. Everywhere I search, the O-rings offered are for sealing the glass, but nothing for the Nano's AFC. Now, the Subtank Mini O-rings packs do include the AFC O-ring. I don't know why Kanger would neglect this O-ring for the Nano. 