This is the removable sleeve and locking nut that converts the drive speed of the Akai 4000 series Reel-to-reel players. Because it is removable it is often lost. Simply slots over and locks in place.
Silver locking nut. The sleeve is aluminium. Fits perfectly with no detectable audio wobble.
Fits 4000D, 4000DS, 4000DS MK 2, 4000DB, GX-4000DB, GX-4000DS