Check out the OXVA UNI Coil Based Airflow Control Ring, a replacement part for those that lose the original one, implementing a dual slotted airflow control ring, threaded coil installation, and is adjustable.
OXVA UNI Coil Based Airflow Control Ring Features:
Threaded Coil Connection
Dual Slotted Airflow Control Ring
Compatible with the OXVA Uni Coils 0.3ohm, 0.5ohm and 1.0 ohm.
Package : 1pc/bag