Pogoplug Series 4 accommodates a standard 9.5mm 2.5" GoFlex drive. Our biggest storage capacity right now for 9.5mm Seagate drives is 750 GB. Larger capacity 2.5" drives have a thickness of 12.5mm and may not fit. Seagate’s older FreePlay 1TB does not fit. Plastic wrapped 12.5mm will definitely not fit.