P class blades are end of life, it's all C class now. If you have a P class chassis then you can put the P class blade server in it, if you haven't got a chassis it is no use to you whatsoever. Blades are like normal servers but have no PSUs or fans - these being part of the enclosure. It also requires additional infrastructure (LAN and SAN switches) to be installed into the enclosure to connect it to the outside world.
