About BT: Poor supply chain of RH products, prompted a new manufacturer to enter the channel with BT Mobile Racks. All BT products are sku compatible with RH series Mobile Racks, including advanced features and upgrades not available on RH products. Features of the BT32 include:

Rubberized footprint on the tray (similar to Compaq Hot Plug Drives)
Easy button depress to remove tray lid
Rubberized Hard Disk shock-absorb gaskets on sidemount
Raised foundation for harddisk