Tool free, Screw-less, and Tray-less structure.Patented design push bar, it connects to the door. And it gives very smooth feel while inserting and ejecting the HDD. Easy but safe open bottom and nice decorated silver trim on front panel. Well measured and presiced mechanical, fits one 2.5" SATA hard drive with good protection and smooth operation. NSS (Neutral Safety Switch) connector, give 50,000 duty cycle to the hard drive under frequent hot-swap environment.