The iMac G5 is a space-saving all-in-one computer. The iMac has a G5-based logic board, a widescreen flat-panel display, a slot-load optical drive, a hard disk and stereo speakers, all within a 5 cm thin enclosure. The iMac G5 comes in two sizes: the 17-inch iMac and the 20-inch iMac which can show more than two full pages, side by side, on its display. The luminous twin-layer plastic enclosure hangs suspended from an anodised aluminium stand, attached at its centre of gravity. The foot is formed from a single sheet of anodised aluminium that rolls into the rear of the enclosure with no visible mechanism. Adjustments to the iMac's display viewing angle can be made with the touch of a finger. The iMac smoothly tilts from 25 degrees backward to 5 degrees forward. The ultra-quiet blowers draw cool air into the system through the speaker grill. Advanced thermal software spins the fan as fast or slow as needed, for a whisper-quiet operation. A slit in the back of the case allows heat to escape through the top. By unfastening three screws along the bottom edge, the rear cover can be removed, exposing the whole system for upgrades and service.