While other OEMs are having trouble mass producing their devices, Samsung is expecting to sell 10 Million Galaxy S IV devices in the first month of launch. Few days ago, we heard that HTC was having troubles manufacturing its flagship device of the year, the HTC One, because of its all aluminium body. This is exactly the reason why Samsung uses plastic instead of other materials in their high-end devices, as they need to mass produce their devices at a very high rate due to the demand of their products and they can't afford to go out of stock.
The Galaxy S IV is rumoured to feature an Exynos 5 Octa (8-Core) CPU, PowerVR SGX 544MP GPU, 4.99″ PHOLED Full HD Resolution Display, 2GB of RAM, 13 Megapixel Rear facing Camera capable of shooting 1080p Full HD Videos at 30FPS, 2.1 Megapixel front facing camera capable of shooting 1080p HD Videos and run Android 4.2.1 Jelly Bean out of the box.