HP Hard Drive Tray MPN 5070-3836.
These are used in a variety of HP MediaSmart and Data Vault NAS units.
Each holds a single 3.5" drive and slides into the NAS unit to align the drive with the backplane interface.
This can also accommodate 2.5" to 3.5" drive adapters so 2.5" drives can be used in these NAS units.
This listing is for two drive trays. If you need one, you probably want a spare, so have two.
This item is sold as-is with no returns. I'll test it by verifying it slides in and out of one of my MediaSmart servers prior to shipping.
Please review my response to see that I am an honest seller.
Please ask any questions prior to purchase and I will be happy to answer them.