Seagate has shipped the first 3.5-inch desktop hard drive employing Perpendicular Recording (PR). Perpendicular Recording is a technique used in hard drive design that adds capacity and speed. This new 3.5-inch desktop hard drive is the Seagate Cheetah 15K.5. Using PR, areal density has been doubled up to 73GB per platter for up to 300GB per drive. The drive spins at 15,000rpm, and has a sustained transfer rate of 125MB per second.