This product is either discontinued or we cannot get that from suppliers.
Qnap SP-ES-TRAY-LOCK HDD Tray Of ES Nas Series ES1640DC V2 NAS Accessories, Drive Bay Adapter, Expansion Bays-1, 2.5" / 3.5" Bays-1, FF Internal, Drive Bay Width 3.5".
The QNAP Hard Drive Tray lets you quickly install an optional 2.5" or 3.5" storage drive in an ES series NAS server. The spare tray helps you install a new drive in the server without spending time to remove a defective drive from its tray.