This product is either discontinued or we cannot get that from suppliers.
Qnap TRAY-35-NK-BLK001 HDD Tray for 3.5" and 2.5" drives without key lock, Black, Plastic, Tool-less for 3.5" HDD installation, Two fixers & 6 x screws for 2.5" HDD included.
Qnap HDD Tray For TAS-168 TAS-268 TS-128 TS-228 NAS Accessories (TRAY-35-NK-BLK001).