This product is either discontinued or we cannot get that from suppliers.
Qnap Controller Fru For CTL-EJ1600-V2-FAN, Including Fan NAS Accessories, The EJ1600 v2 Expansion Enclosure.
The QNAP Field-Replaceable Controller Unit is a spare controller for their EJ1600 v2 16-Bay Expansion Enclosure. It includes a fan.