BP-TL2131SAC designed to fit in with two open bays and can put in three 3, 5 HDD, Trayless design makes HDD installing easier, This is the most economic solution for Backplane cage, It combines SAS and SATA-I, II interface, and the transfer rate can up to 3, 0Gbps, It supports Hot-Swap, and the external fan is replaceable, Support Hot-Swap, RAID 0/1/5, Aluminum Design, Mechanical Sliding Lock, Trayless Design, Easy Swap In/Out HDD, Support SATA and SAS up to 3Gb/s, Meshed Air-Ventilation Holes, Led for Power Indication, Specifications:, Interface: SATA I, SATA II and SAS Primary Channel, Form Factor: For 3 x 3, 5"" SAS/SATA HDD; 2 x 5, 25"" Bay for 3HDD, Fan: 50mm x 1, Power Connector: 4pin Power Connector x 2, HDD Connection: Cableless HDD Connection, Transfer Rate: Upto 3, 0 Gbps (SAS and SATA II) and 1, 5 Gbps (SATA I), Material: Aluminum Frame and Plastic Bezel, Dimensions: 5, 7""W x 3, 3""H x 7, 3""L, SKU: ATHCPC009