This is a new product that Hobbyking is selling. It more or less resembles (IMHO) the AR.Drone frame. The motors are place in the center of the arms and the propellers are protected by EPP foam rings.
The 450mm width is measured motor shaft to motor shaft. The actual size of the frame is 835mm which makes it quite big.
To complete this quadcopter you will need 4 motors and 8-10 inch propellers, 4 esc's, a quadcopter control board and a 3S 1300-1800 mah Battery. I think even a bigger battery should work.
The frame is yours for US$ 22.49
More information on the Hobbyking site: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=25420&aff=5361