Designed specifically for the existing 3.5" bays of newer PC chassis, backplanes and RAID-type enclosures. Supports any capacity 2.5" SATA or SAS HDD, as well as SSD (Solid State) and makes it appear to the system as a 3.5" HDD. Hard drive not included. Accommodates many heights - 9.5mm, 12mm, 15mm...even up to 22mm! Metal construction and airflow spacing design for heat dissipation. Ideal for transactional workstations because 2.5" HDDs have faster seek times and process transactions faster than a 3.5" HDD. No circuit board; no problems with 3G (moving to 6G) interface to 2.5" HDD.