High performance- combining large capacity with SATA 3gbps interface and high-speed cache, these 3.5" Drives delivers solid performance for the demanding multimedia applications. Long-term reliability- with a MTBF of 1 million hours, the wd av internal hard drives can withstand high-temperature always-on streaming digital audio/video environments such as PVR/DVD, DVR recorders and surveillance video recorders. Silkstream technology- powered by the silkstream technology, the wd av drives ensures smooth, continuous digital video playback of up to twelve simultaneous HD streams.(assumes host transfer block size of 2 MB per stream.) preemptive wear leveling (PLW)- the drive arm frequently sweeps across the disk to reduce uneven wear on the drive surface common to audio video streaming applications. Wd av drives are the cool, quiet and reliable choice for always-on 24/7 av applications. They are designed for media center, media server, surveillance, digital signage and other av systems requiring perfect audio and video, low heat, low power and long term reliability.